Commit Graph

4322 Commits

Author SHA1 Message Date
Jamal Hadi Salim
729c4896ab net/sched: sch_htb: limit htb_classify inner-class filter hops
htb_classify() follows each filter-selected inner class by switching
to cl->filter_list, but never bounds the number of hops. A filter on
an inner class can point back to itself or to another inner class that
points back, creating an infinite loop in the packet classification
path with the qdisc lock held and BH disabled — a soft lockup / panic
from a single packet.

Bound the traversal with a hop counter and drop the packet with a
rate-limited warning once the bound is exceeded. The counter is
incremented at the point the inner filter chain is picked up, after the
TC_ACT_* switch has consumed the classifier verdict, so a terminal
TC_ACT_QUEUED/STOLEN/TRAP on the last permitted chain still sets *qerr
to __NET_XMIT_STOLEN and the packet is not charged as a drop by this
qdisc or its parent.

The bound is TC_HTB_MAXDEPTH, taken from HTB's own parameters rather than
from the qdisc hierarchy depth limit. Class levels run from 0 to
TC_HTB_MAXDEPTH - 1, so a traversal that strictly descends in level can
take at most TC_HTB_MAXDEPTH hops. That descent is what a sane
configuration does, but it is assumed here rather than enforced:
htb_find() resolves a classid against every class in the qdisc, so a
filter may equally select a sibling or an ancestor. The normal
root -> inner -> leaf path takes a single hop, so the bound does not
affect legitimate classification.

htb_classify() can now return NULL irrespective of CONFIG_NET_CLS_ACT,
whereas previously every NULL return sat inside that ifdef. The NULL
handler in htb_enqueue() therefore cannot stay conditional either, so
drop the ifdef around it. This matches hfsc_enqueue(), which has always
handled a NULL class unconditionally. Without it, a kernel built
without actions would dereference a NULL class instead of dropping.

Conditions to recreate the bug:
- CONFIG_NET_SCHED, CONFIG_NET_SCH_HTB, CONFIG_NET_CLS_U32,
  CONFIG_LOCKUP_DETECTOR.
- Create an HTB qdisc on a device (e.g. lo), add an inner class
  1:1 with a leaf child 1:10, install a root u32 filter selecting
  1:1, and an inner-class u32 filter on 1:1 also selecting 1:1.
- Send one packet (ping). On the unfixed kernel the classify loop
  spins with the qdisc lock held; with softlockup_panic=1 it panics.
- Reachable from unprivileged user via unshare -Urn (CAP_NET_ADMIN).

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: Vega <vega@nebusec.ai>
Co-developed-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260826143339.271935-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-27 12:47:58 -07:00
Jamal Hadi Salim
8f735d6438 net/sched: bound qdisc_pkt_len to prevent qdisc soft lockup
qdisc_get_stab() accepts a user-supplied size table, and
__qdisc_calculate_pkt_len() amplifies qdisc_pkt_len() through the
overhead, the size-table data (u16), and size_log (up to
STAB_SIZE_LOG_MAX). A crafted stab can therefore set qdisc_pkt_len()
to ~1 GiB for an ordinary skb. Per-flow deficit schedulers such as
DRR and ETS replenish one quantum per loop iteration; with a tiny
quantum (1) they spin billions of times under the qdisc lock,
producing a soft lockup / RCU stall as illustrated by vega@nebusec.ai.

Cap the final qdisc_pkt_len() to QDISC_PKT_LEN_MAX so the size-table
amplification cannot drive deficit schedulers into an unbounded loop.
A legitimate size table (e.g. qfq's overhead 999999999, which is
handled by dropping) is still accepted.

Introduce cap QDISC_PKT_LEN_MAX (1 << 20) = 1 MiB which is well above
any legitimate single-skb wire length: the largest current skb->len
is GSO_MAX_SIZE (524280), and an ATM-style size table (53/48 cell tax)
amplifies that to ~578 KB, both comfortably below 1 MiB. At the same
time, 1 MiB bounds the deficit refill loop to ~1M iterations per
packet with quantum=1, which completes in a few milliseconds well
under the demonstrated softlockup threshold (~10^9 iterations).

Conditions to recreate the bug:
- CONFIG_NET_SCHED=y, CONFIG_NET_SCH_DRR=y (or CONFIG_NET_SCH_ETS=y).
- Attach a DRR (or ETS) root qdisc with a crafted TCA_STAB that
  amplifies qdisc_pkt_len to ~1 GiB (e.g. size_log=15, data=[32768]).
- Add a class with a tiny quantum of 1 and send one small packet; the
  deficit loop spins billions of times under the qdisc lock and trips
  the softlockup detector (panic with kernel.softlockup_panic=1).
- Reachable as root or from an unprivileged user in a fresh user+net
  namespace (unshare -Urn) with namespace-local CAP_NET_ADMIN.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260825081403.133992-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-27 12:12:36 -07:00
Breno Leitao
82aeed2400 net: fix spurious TX timeout after dev_activate()
While debugging another issue today, I found out that my TX queue is
reported as stopped for 4294907392 ms (49.7 days), on a machine that
had been up for four minutes.

    bnxt_en 0002:01:00.0 eth0: NETDEV WATCHDOG: CPU: 28: transmit queue 23 timed out 4294907392 ms

4294907392 is not an elapsed time. It is the value of jiffies at that
moment: INITIAL_JIFFIES is 4294667296, which leaves jiffies 59 seconds
short of wrapping.

dev_activate() runs transition_one_qdisc() over every TX queue, which
resets trans_start to 0, and then stamps only queue 0 through
netif_trans_update().

Stamp jiffies instead. A queue stopped across dev_activate() now gets a
full watchdog_timeo of grace, and is still reported if it is stopped
that long.

Fixes: 9b36627ace ("net: remove dev->trans_start")
Cc: stable@vger.kernel.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20260825-trans_start-v2-1-286b4d6d70cb@debian.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-27 10:25:59 +02:00
Victor Nogueira
dc4b95b8fe net/sched: sch_teql: restore skb->dev on the slave failure path
teql_master_xmit() sets skb->dev = slave before calling the slave's
ndo_start_xmit(), but never restores it when that transmit fails. The
skb then walks on to the next slave still pointing at the previous one.

If a later slave has no resolved neighbour, teql_resolve() hands the skb
to neigh_event_send(), which queues it on that neighbour's arp_queue
with the stale skb->dev. skb->dev holds no reference, so deleting the
previous slave frees the net_device while the skb is still queued.
Whatever runs next on that skb - arp_error_report() on timeout, or
neigh_direct_output() -> dev_queue_xmit() once the neighbour resolves -
causes a UAF like the one below:

BUG: KASAN: slab-use-after-free in __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))
Read of size 4 at addr ffff888106e100b0 by task flood_packet/527
CPU: 0 UID: 0 PID: 527 Comm: flood_packet Not tainted 7.2.0-rc6-g594d90519502 #1 PREEMPT(lazy)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
? __pfx__raw_spin_lock_irqsave (./include/asm-generic/qrwlock.h:122 (discriminator 4))
? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))
kasan_report (mm/kasan/report.c:595)
? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))
__icmp_send (net/ipv4/icmp.c:914 (discriminator 2))
[...]
ipv4_link_failure (net/ipv4/route.c:1251 net/ipv4/route.c:1258)
? __pfx_ipv4_link_failure (./include/linux/skbuff.h:4327)
? _raw_write_lock (./include/linux/instrumented.h:55 ./include/linux/atomic/atomic-instrumented.h:1301 ./include/asm-generic/qrwlock.h:98 ./include/linux/rwlock_api_smp.h:230 kernel/locking/spinlock.c:304)
? __pfx__raw_write_lock (kernel/locking/spinlock.c:175)
arp_error_report (./include/net/dst.h:438 net/ipv4/arp.c:296)
neigh_invalidate (net/core/neighbour.c:1077)
neigh_timer_handler (net/core/neighbour.c:1169)
[...]
Allocated by task 505:
kasan_save_stack (mm/kasan/common.c:57)
kasan_save_track (mm/kasan/common.c:78)
__kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)
__kvmalloc_node_noprof (./include/linux/kasan.h:263 mm/slub.c:5334 mm/slub.c:6905)
alloc_netdev_mqs (net/core/dev.c:12055 (discriminator 2))
rtnl_create_link (net/core/rtnetlink.c:3721)
rtnl_newlink (net/core/rtnetlink.c:3903 net/core/rtnetlink.c:4044 net/core/rtnetlink.c:4159)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)
[...]
Freed by task 536:
kasan_save_stack (mm/kasan/common.c:57)
kasan_save_track (mm/kasan/common.c:78)
kasan_save_free_info (mm/kasan/generic.c:584)
__kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285)
kfree (./include/linux/kasan.h:235 mm/slub.c:2677 mm/slub.c:6377 mm/slub.c:6692)
device_release (drivers/base/core.c:2636)
kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)
netdev_run_todo (net/core/dev.c:11756)
rtnl_dellink (net/core/rtnetlink.c:157 ./include/linux/rtnetlink.h:135 net/core/rtnetlink.c:3651)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)
[...]

Fix this by restoring skb->dev to the master at the end of each slave's
iteration.

Fixes: 0cc0c2e661 ("net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit")
Reported-by: Vega <vega@nebusec.ai>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260824115928.4099988-1-victor@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 15:24:35 +02:00
Jamal Hadi Salim
816e90057a net/sched: sfq: clamp quantum to avoid signed overflow soft lockup
sfq_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) (unsigned). A
device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU
2147483634) makes psched_mtu() return 0x80000000, so slot->allot = INT_MIN
and INT_MIN + INT_MIN toggles between INT_MIN and 0 forever, spinning
sfq_dequeue() under the qdisc lock.

Clamp the quantum to [256, 1 << 20] so the refill loop terminates. The
lower bound also covers q->quantum == 0 (psched_mtu() returning 0),
which spins sfq_dequeue() identically. sfq_change() already rejects a
negative quantum, so only the init path was exposed.

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy
device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-7-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Jamal Hadi Salim
2164b512b9 net/sched: hhf: clamp quantum before hhf_change() to avoid overflow
hhf_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) with no overflow
check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting
MTU 2147483634) makes weight * quantum overflow the signed deficit in
hhf_dequeue(), spinning forever.

Clamp q->quantum before hhf_change() so both the opt and !opt paths see
a sane quantum. Without this, bare "tc qdisc add ... hhf" succeeds with
a clamped quantum but "tc qdisc add ... hhf limit 1000" (any option
present) fails with -EINVAL because hhf_change() re-validates the
unclamped default (sch_hhf.c:559). 256 matches fq_codel's floor and is
a sane minimum for a DRR quantum.

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy
device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: 10239edf86 ("net-qdisc-hhf: Heavy-Hitter Filter (HHF) qdisc")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-6-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Jamal Hadi Salim
c86cd7ed0b net/sched: fq_pie: clamp default quantum to avoid signed overflow
fq_pie_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without
clamping. A device with a huge MTU (e.g. dummy with max_mtu == 0
accepting MTU 2147483634) makes psched_mtu() return 0x80000000, which
overflows the signed flow->deficit to INT_MIN in fq_pie_qdisc_dequeue(),
causing an infinite loop and soft lockup. Emulate fq_pie_policy which
is already bounded to [1, 1 << 20]; clamp the default to [256, 1 << 20].
256 matches fq_codel's floor and is a sane minimum for a DRR quantum.

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy
device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: ec97ecf1eb ("net: sched: add Flow Queue PIE packet scheduler")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-5-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Jamal Hadi Salim
6439461f16 net/sched: sch_codel: clamp default mtu to avoid disabling CoDel
codel_init() sets q->params.mtu = psched_mtu(qdisc_dev(sch)) without
clamping. A device with a huge MTU (e.g. dummy with max_mtu == 0
accepting MTU 2147483634) makes psched_mtu() return 0x80000000. In
codel_should_drop() the test "*backlog <= params->mtu" then compares
the backlog against ~2 GiB; with the default sch->limit of
DEFAULT_CODEL_LIMIT (1000) packets the backlog can never reach it, so
the test is always true and CoDel is silently and completely disabled
i.e no drops, no ECN marking, codel degrades to a tail-drop FIFO.
codel_change() never updates params.mtu, so the init path is the only
place to clamp it. Constrain to [256, 1 << 20], matching the fq_codel
bound; 256 is a sane floor that only makes CoDel slightly more willing
to act on very small queues, which is the safe direction.

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy
device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: 76e3cc126b ("codel: Controlled Delay AQM")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-4-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Jamal Hadi Salim
d9ebd8f9aa net/sched: fq_codel: clamp default quantum and mtu
fq_codel_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without
clamping. A device with a huge MTU (e.g. dummy with max_mtu == 0
accepting MTU 2147483634) makes psched_mtu() return 0x80000000, which
overflows the signed flow->deficit to INT_MIN in fq_codel_dequeue(),
causing an infinite loop and soft lockup. Emulate fq_codel_change()
and constrain to [256, FQ_CODEL_QUANTUM_MAX].

The same unclamped psched_mtu() is assigned to q->cparams.mtu a bit
below, and fq_codel_change() never updates it. codel_should_drop()
tests "*backlog <= params->mtu"; with mtu == 0x80000000 (~2 GiB) and
the default 32 MiB memory_limit, the test is always true, so CoDel is
silently and completely disabled (no drops, no ECN). Declare a single
clamped mtu and assign both q->quantum and q->cparams.mtu from it,
which also removes the double psched_mtu() call.

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy
device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: 4b549a2ef4 ("fq_codel: Fair Queue Codel AQM")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-3-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Jamal Hadi Salim
709f34f7c2 net/sched: fq: add overflow bounds to quantum and initial quantum
fq_init() computes quantum = 2 * psched_mtu() and initial_quantum = 10 *
psched_mtu() with no overflow check. A device with a huge MTU (e.g. dummy
with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return
0x80000000; the 2 * and 10 * multiplications wrap to 0 in 32-bit
arithmetic, so q->quantum == 0. Then in fq_dequeue() the credit-refill
loop adds 0 to f->credit (which stays <= 0) and goto begin loops
forever under the qdisc lock, creating a soft lockup.

Clamp psched_mtu() to [1, 1 << 20] before multiplying so the product
cannot wrap, then cap the result at 1 << 20, matching the bound already
enforced on TCA_FQ_QUANTUM in fq_change().

Conditions to recreate the bug: a device whose MTU (plus
hard_header_len) is large enough that 2 * psched_mtu() wraps (e.g. a
dummy device with max_mtu == 0 accepting MTU 2147483634). Requires
CAP_NET_ADMIN in a user namespace.

Fixes: afe4fd0624 ("pkt_sched: fq: Fair Queue packet scheduler")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260822195509.112717-2-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 13:09:32 +02:00
Eric Dumazet
81d0d1e64f net/sched: act_skbmod: fix length calculations and avoid invalid header warnings
syzbot reported a warning in skb_network_header_len() triggered
by tcf_skbmod_act():

  !skb_transport_header_was_set(skb)
  WARNING: CPU: 0 PID: 14949 at include/linux/skbuff.h:3243 skb_network_header_len include/linux/skbuff.h:3243 [inline]
  WARNING: CPU: 0 PID: 14949 at net/sched/act_skbmod.c:55 tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55

There are a few issues in tcf_skbmod_act():

1. Calling skb_network_header_len() assumes skb->transport_header is set,
   which is not guaranteed when tcf_skbmod_act() runs at TC ingress.
2. Unconditionally calling skb_mac_header_len() at the beginning of
   tcf_skbmod_act() triggers a warning on L3 devices (e.g. TUN) where the
   MAC header is unset, evaluating to an underflowed garbage length.
3. On TC ingress, skb->data points to the network header. Adding the MAC
   header length to the IP header length causes skb_ensure_writable() to
   request more bytes than the actual IP packet length, dropping valid
   short packets (e.g. 28-byte UDP/IPv4 packets).

Fix these by:
- Using skb_network_offset(skb) + sizeof(struct iphdr/ipv6hdr) for
  SKBMOD_F_ECN so that the required length is correctly calculated on
  both ingress (offset == 0) and egress (offset == mac_len).
- Setting max_edit_len to ETH_HLEN for Ethernet header modifications
  after validating ARPHRD_ETHER.

Fixes: 56af5e749f ("net/sched: act_skbmod: Add SKBMOD_F_ECN option support")
Reported-by: syzbot+1d56f14f95c0480cfdc9@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6a8b39c0.dbb3a75c.13dd47.0051.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260823182241.1958695-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-25 11:04:12 +02:00
Victor Nogueira
5b483f7791 net/sched: act_ife: Only operate on Ethernet frames
act_ife encapsulates/decapsulates the original Ethernet header and uses
skb->dev->hard_header_len as the length of that header. That is only
correct for Ethernet devices: on a device where hard_header_len does not
match the L2 header that was actually pulled (PPP reports PPP_HDRLEN
while nothing is stripped on ingress), the ingress skb_push()/skb_pull()
use the wrong length and can hit skb_under_panic when headroom is tight.

IFE is Ethernet-only by design - it builds an outer ethhdr, rewrites
h_source/h_dest/h_proto, and calls eth_type_trans() on decode - so
instead of trying to make the offsets work for arbitrary link types,
simply drop packets that do not carry an Ethernet header.

Checking skb->dev->type alone is not enough. We have to cater for a
corner case where mirred can redirect an skb from a non-Ethernet device
to an Ethernet one, and skb->dev then says nothing about the framing the
skb actually has: an skb redirected from ppp0 reaches the target's ingress
hook with mac_len 0 and no Ethernet header at all. So at ingress also
require mac_len to be ETH_HLEN. On egress mac_len is not maintained, so
the device type is all we have; a bogus redirect there yields a malformed
frame rather than an out-of-bounds push, and it would be malformed with or
without IFE.

That corner case is not theoretical - redirecting from ppp0 into a veth
that has an ife encode action on its ingress hook panics without this
patch:

  skbuff: skb_under_panic: len:98 put:14 head:ffff88800e410000
          data:ffff88800e40fff5 tail:0x57 end:0x640 dev:veth3
  kernel BUG at net/core/skbuff.c:214!
  Call Trace:
   skb_push (net/core/skbuff.c:224 net/core/skbuff.c:2657)
   tcf_ife_act (net/sched/act_ife.c:829 net/sched/act_ife.c:874)
   tc_run (net/core/dev.c:4463)
   netif_receive_skb (net/core/dev.c:6463 net/core/dev.c:6522)
   tcf_mirred_to_dev (net/sched/act_mirred.c:248 net/sched/act_mirred.c:328)
   tcf_mirred_act (net/sched/act_mirred.c:489)
   tc_run (net/core/dev.c:4463)
   process_backlog (net/core/dev.c:6728)

With Ethernet framing guaranteed, use ETH_HLEN instead of
hard_header_len.

Fixes: 295a6e06d2 ("net/sched: act_ife: Change to use ife module")
Reported-by: vega@nebusec.ai
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260821164031.32824-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-24 11:59:59 -07:00
Giuseppe Piscitelli
7cbfb18094 net/sched: sch_cake: fix autorate reconfiguration throttling
CAKE's autorate-ingress path intends to limit shaper reconfiguration to
once per 250 ms, but last_reconfig_time is only checked and never updated.
Since the field stays zero, every qualifying capacity-estimate window can
call cake_reconfigure(), causing avoidable rate churn and scheduler work
under bursty traffic.

Store the current timestamp when autorate actually reconfigures the qdisc
so the guard enforces the intended interval.

Fixes: 7298de9cd7 ("sch_cake: Add ingress mode")
Signed-off-by: Giuseppe Piscitelli <ooonea@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260820154503.892214-1-ooonea@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-22 13:51:40 -07:00
Eric Dumazet
137b8ae233 net_sched: sch_fq: fix pacing delay underflow with pacing offload
When pacing offload is enabled (q->offload_horizon > 0),
FQ can dequeue packets early (now < f->time_next_packet).

In this case, the drift calculation (now - f->time_next_packet)
underflows to a large unsigned value.

min(len/2, now - f->time_next_packet) then evaluates to len/2,
incorrectly halving the pacing delay for the next packet.

Fix this by only applying drift compensation if now > f->time_next_packet.

This bug was triggered when flow_max_rate was set on the qdisc
or for non EDT packets (packets with a zero skb->tstamp).

Fixes: f26080d470 ("net_sched: sch_fq: add the ability to offload pacing")
Reported-by: Willem de Bruijn <willemb@google.com>
Closes: https://lore.kernel.org/netdev/CANn89iK6O7ujR9zCJzd04MNLQoDi3mA+HWsR-hgQWYzLS3gZfw@mail.gmail.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260820120706.1995449-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-22 13:47:53 -07:00
Jamal Hadi Salim
1beb81947e net/sched: account classifier filter allocations to memcg
Allocations in the tc classifier *_change() paths (filter objects,
per-CPU counters, and per-filter aux data) use plain GFP_KERNEL without
__GFP_ACCOUNT, allowing unprivileged users to pin kernel memory outside
memcg charging. The shared tcf_exts_init_ex() action array allocation in
cls_api.c was also uncharged; this patch closes it along with the
per-classifier filter-object/percpu/aux allocations that remain
unaccounted.

Add GFP_KERNEL_ACCOUNT to:
- the shared tcf_exts_init_ex() action array (cls_api.c), common to every
  filter of every classifier (32 pointers, 256 bytes);
- the filter-object, per-CPU-counter, and per-filter aux allocations in
  cls_basic, cls_bpf, cls_cgroup, cls_flow, cls_flower, cls_fw,
  cls_matchall, cls_route and cls_u32;
- the u32_init_knode() replace-path knode allocation (cls_u32.c), which
  allocates the same struct tc_u_knode + sel.keys on every replace of an
  existing knode and was missed by the create-path-only conversion.

Also fix the cls_basic error path: basic_change() inserts fnew into the
IDR before allocating the per-CPU counter. If alloc_percpu() fails the
errout path kfree'd fnew without idr_remove, leaving a dangling pointer
in the IDR. With GFP_KERNEL_ACCOUNT the percpu alloc becomes failable
on demand (memcg at memory.max), making the dead path attacker-reachable
and burning the handle permanently. Add the idr_remove on the percpu
failure path, matching the basic_set_parms failure-path pattern.

Note: vega@nebusec.ai provided a poc for basic_cls, but it was easy to
extend to the other classifiers.

Conditions to recreate the bug:
- CONFIG_NET_SCHED, CONFIG_NET_CLS_* (the classifier being used),
  CONFIG_NET_CLS_ACT, CONFIG_MEMCG, CONFIG_USER_NS, CONFIG_NET_NS.
- Unprivileged user in a fresh user+network namespace (unshare -Urn),
  or root with CAP_NET_ADMIN.
- Create a large number of tc filters (e.g. tc filter add dev lo
  ingress ... <classifier> ...) while watching a memcg-limited cgroup:
  system slab grows far faster than memory.current, pinning kernel
  memory outside memcg charging.

Fixes: 0da974f4f3 ("[NET]: Conversions from kmalloc+memset to k(z|c)alloc.")
Reported-by: vega@nebusec.ai
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260819143733.57538-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-22 13:02:32 -07:00
Jamal Hadi Salim
4c660ee8c8 net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue
gred_enqueue(), bfifo_enqueue() and plug_enqueue() admit a packet when the
current backlog plus the packet length fits within the queue limit:

  sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (gred default VQ)
  gred_backlog+qdisc_pkt_len(skb) <= q->limit  (gred configured VQ)
  sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (bfifo)
  sch->qstats.backlog + skb->len <= q->limit             (plug)

sch->qstats.backlog and q->backlog are u32, and qdisc_pkt_len()/skb->len
are unsigned int, so all sums are computed in 32 bits and wrap at 2^32.
Once the true backlog exceeds 4 GiB the wrapped sum becomes small and
admission keeps succeeding, so the queue grows without bound and the kernel
can be driven to OOM.

Promote the sums to u64 so admission stops once the true backlog exceeds
the limit.  The limit is u32, so the bounded queue stays below 2^32 and
the stored u32 backlog never wraps.

The bug can only be reproduced as root (albeit with ridiculous setup):
 attach a gred (or bfifo/plug) qdisc with a limit near 4 GiB,
 leaving the default VQ unconfigured (for gred), and drive >4 GiB of
 queued traffic (e.g. via a size table / stab to inflate qdisc_pkt_len,
 or sustained high-rate traffic). The u32 backlog+len sum wraps at 2^32,
 admission keeps succeeding, and the queue grows unboundedly to OOM.

Fixes: a3eb95f891 ("net_sched: gred: add TCA_GRED_LIMIT attribute")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260818095927.15901-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-20 13:28:45 -07:00
Victor Nogueira
8e2efb3f45 net/sched: add get_fill_size callbacks for actions missing them
Several tc actions - act_police, act_bpf, act_pedit, act_ife, act_sample,
act_ct, act_ctinfo and act_tunnel_key among them - provide no
get_fill_size() callback, so tcf_action_fill_size() falls back to
tcf_action_shared_attrs_size() which does not account for the
action-specific netlink attributes emitted inside TCA_ACT_OPTIONS by
their dump functions.

When an RTM_NEWACTION request with NLM_F_ECHO (or an RTNLGRP_TC
listener) creates several actions, tcf_add_notify_msg() allocates the
echo skb from this underestimated size. When this happens, the act_api
code fails to add all of the fields to the netlink message and, thus,
fails to send it. Issue is that, when that happens, this failure doesn't
stop the action instances from being added. So any user watching these
events will be under the false impression that no actions were created at
all.

For example, act_pedit overruns with 32 actions of four munge keys each,
act_police with 32 policers once the optional rate/peakrate/result/avrate
attributes are present.

To fix this, add the missing get_fill_size callbacks returning the
worst-case size of each action's dump attributes, following the pattern
used by act_gact/act_skbedit/act_vlan. Also widen the TCA_GACT_TM
accounting in tcf_action_shared_attrs_size() to nla_total_size_64bit(),
since actions dump their tcf_t with nla_put_64bit(), which may be
preceded by an NLA_PAD attribute.

Note: We only provided fixes for the actions we reproduced this bug with
as of today. We can send a separate hardening patch for the remaining
actions to net-next later. The other pre-existing issues, pointed out by
Clashiko [1], will be fixed in upcoming patches.

[1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260810164357.1653956-1-victor%40mojatatu.com

Fixes: 4e76e75d6a ("net sched actions: calculate add/delete event message size")
Reported-by: Vega <vega@nebusec.ai>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260816201327.2435335-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-20 12:16:43 -07:00
Eric Dumazet
51b0aaafd9 net: add READ_ONCE()/WRITE_ONCE() annotations for dev->prio_tc_map
Concurrent fast-path readers access dev->prio_tc_map (e.g. via
skb_tx_hash(), netdev_get_prio_tc_map(), and qdiscs) while writers
update entries in dev->prio_tc_map or reset/clear the map via
netdev_reset_tc() and netdev_unbind_sb_channel().

Furthermore, memset() in netdev_reset_tc() and
netdev_unbind_sb_channel() provides no guarantee of performing
atomic word/byte stores.

Add READ_ONCE() and WRITE_ONCE() annotations to netdev_get_prio_tc_map()
and netdev_set_prio_tc_map(), replace memset() in dev.c with explicit
WRITE_ONCE() loops, and update direct array accesses in qdiscs to use
netdev_get_prio_tc_map().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260812085440.3917924-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17 10:27:48 -07:00
Eric Dumazet
0c6c32a8c8 net: add READ_ONCE()/WRITE_ONCE() annotations for dev->num_tc
Several fast-path and control-path lockless readers access dev->num_tc
(e.g., skb_tx_hash(), netdev_txq_to_tc(), netdev_get_num_tc(), and
qdisc/driver lookups) while concurrent writers update dev->num_tc
during TC setup, device reset, or channel configuration.

Add READ_ONCE() and WRITE_ONCE() annotations to prevent compiler
reordering and load/store tearing when accessing dev->num_tc.

Update inline helpers in netdevice.h (netdev_get_num_tc(),
netdev_set_prio_tc_map(), and netdev_get_sb_channel()) as well as
writers and lockless readers in core networking code and drivers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260812085440.3917924-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17 10:27:48 -07:00
Eric Dumazet
21ef2d065a net: prevent torn reads in netdev_tc_txq
netdev_set_tc_queue() (and related helpers/drivers such as
netdev_bind_sb_channel_queue(), netdev_reset_tc(), and
netdev_unbind_sb_channel()) perform separate 16-bit writes to
dev->tc_to_txq[tc].count and dev->tc_to_txq[tc].offset.

Furthermore, memset() in netdev_reset_tc() and
netdev_unbind_sb_channel() provides no guarantee of performing
full 32-bit word stores.

Concurrent lockless readers (e.g. skb_tx_hash(), netdev_txq_to_tc(),
ixgbe_select_queue(), taprio, mqprio, FPE drivers) can observe torn
values where offset and count belong to inconsistent configurations.

Redefine struct netdev_tc_txq to embed count and offset inside a union
with a u32 combined field, allowing atomic manipulation via
READ_ONCE() and WRITE_ONCE().

Update all lockless readers and writers across the kernel to use
READ_ONCE() and WRITE_ONCE() on the combined field.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260812085440.3917924-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17 10:27:48 -07:00
Jakub Kicinski
4cc4f59258 netfilter pull request 26-08-10
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Merge tag 'nf-next-26-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next

Pablo Neira Ayuso says:

====================
Netfilter updates for net

This includes an enhancement to detect ct memleaks easier via
DEBUG_NET and flowtable preparation patches for IPv4 over IPV6
and vice-versa. This also includes a fix for the nft_ct custom
expectation support.

1) Add DEBUG_NET_WARN_ON_ONCE to nf_ct_set() to spot ct memleaks.

2) Pass struct net_device_path_ctx to dev_fill_forward_path() to
   make it easier to pass more parameters to this function.
   From Lorenzo Bianconi.

3) Add ether_type field to net_device_path context structucture.

4) Rename tun.l3_proto field to tun.inner_proto.

5) Rename ctx.tun.proto to ctx.tun.inner_proto.

6) Store ether_type in flowtable context.

7) Move IPv4 and IPv6 xmit path to a helper function.

8) Move encapsulation header parser out of the flowtable lookup
   function.

9) Rework nft_ct custom expectation support to address a possible
   reallocation of ct extension area while expectation list also
   contains expectations. Move datapath to a ct helper to fix it.

10) Ensure timeout is always lowered for the non-closing RST case
    in the TCP connection tracking.

11) Bail out when inserting already dead expectation, this should
    not ever happen, hence report it via DEBUG_NET.

12) Comestic updates for improving the conntrack selftest dump and
    flush userspace program, from Qingshuang Fu.

* tag 'nf-next-26-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  selftests: netfilter: conntrack_dump_flush: remove unused variables and fix typo
  netfilter: nf_conntrack_expect: bail out on insert dead expectations
  netfilter: conntrack: always lower timeout for non-closing RST packets
  netfilter: nft_ct: move custom expectation support to helper
  netfilter: flowtable: detach layer 2 encapsulation parser from lookup
  netfilter: flowtable: move ipv4 and ipv6 xmit path to function
  netfilter: flowtable: store ethertype in flowtable context
  netfilter: flowtable: rename ctx.tun.proto to ctx.tun.inner_proto
  netfilter: flowtable: rename tun.l3_proto to tun.inner_proto
  net: netfilter: add ether_type to net_device_path_ctx and use it
  net: pass net_device_path_ctx to dev_fill_forward_path()
  netfilter: add DEBUG_NET_WARN_ON_ONCE to skb_set_nfct()
====================

Link: https://patch.msgid.link/20260810194015.932627-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-14 12:23:12 -07:00
Jakub Kicinski
3da8c3c8b8 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc8).

No conflicts.

Adjacent changes:

drivers/net/ethernet/wangxun/ngbe/ngbe_main.c
  5f3a13e0bb ("net: ngbe: fix NULL pointer dereference in non-MSI-X interrupt enabling")
  d661abdc30 ("net: ngbe: correct misleading interrupt comment")

drivers/net/ipvlan/ipvlan_main.c
  e16e960d55 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev")
  00a40d8092 ("ipvlan: Support per-netns netdev unregistration.")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-13 11:00:14 -07:00
Jamal Hadi Salim
120977e2c0 net/sched: cls_bpf: reject dev-bound programs bound to a different device
cls_bpf_prog_from_efd() obtained a SCHED_CLS program via
bpf_prog_get_type_dev() but never verified that a device-bound (offloaded)
program's bound netdev matches the TC netdev the classifier is being
attached to. This let a program loaded with prog_ifindex for device A be
attached via cls_bpf + skip_sw to device B; deleting device A then
destroyed the program's offload state while it was still attached to
device B, triggering a netdevsim WARN (panic with panic_on_warn=1).

Mirror the XDP attach path (net/core/dev.c) and reject the attach with
-EINVAL when a dev-bound program's bound device does not match the
target device.

Fixes: 2b3486bc2d ("bpf: Introduce device-bound XDP programs")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/20260809094418.901607-1-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-13 11:08:39 +02:00
Zhang Changzhong
6d3724e616 net/sched: cls_u32: skip hash tables in u32_bind_class()
u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode
through the walker callback. u32_bind_class() unconditionally casts the
passed fh to tc_u_knode and accesses &n->res, so when fh is actually a
tc_u_hnode, which has no tcf_result member, this results in a
slab-out-of-bounds read of res->classid in tc_cls_bind_class().

The issue can be reproduced with the following commands:

    tc qdisc add dev lo root handle 1: hfsc
    tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit
    tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1
    tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit

Fix this by skipping hash tables via the TC_U32_KEY(handle) check.

Fixes: 07d79fc7d9 ("net_sched: add reverse binding for tc class")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/1786089038-36366-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:28:43 -07:00
Jamal Hadi Salim
f60b396ee1 net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain
tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking
rcu_access_pointer(a->goto_chain) and then calling
tcf_action_goto_chain_exec(), which does a second, independent
rcu_dereference_bh(a->goto_chain) read and immediately dereferences
chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact
replace path) can clear a->goto_chain between the two reads, so the second
read returns NULL and tcf_action_goto_chain_exec() dereferences NULL.

Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain
in tcf_action_exec(), checking it once for NULL, and passing the resulting
chain pointer into tcf_action_goto_chain_exec(). This turns the split
check/use into a single check/use on one value.

Fixes: ee3bbfe806 ("net/sched: let actions use RCU to access 'goto_chain'")
Reported-by: vega@nebusec.ai
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20260809090928.868186-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11 18:21:46 -07:00
Hyunjung Ko
8a7ed56167 net/sched: act_ct: fix sk_buff leak when the header checks reject a packet
tcf_ct_handle_fragments() runs its header sanity checks before handing
anything to the defragmentation engine:

	if (family == NFPROTO_IPV4)
		err = tcf_ct_ipv4_is_fragment(skb, &frag);
	else
		err = tcf_ct_ipv6_is_fragment(skb, &frag);
	if (err || !frag)
		return err;

tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM;
tcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of
them frees or queues the skb, so on that path the caller still owns it.

tcf_ct_act() however funnels every non-zero return into the
ownership-transfer exit:

	err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag);
	if (err)
		goto out_frag;
	...
out_frag:
	if (err != -EINPROGRESS)
		tcf_action_inc_drop_qstats(&c->common);
	return TC_ACT_CONSUMED;

TC_ACT_CONSUMED means the action took ownership of the skb, so no caller
frees it - sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for that verdict. The
skb is therefore orphaned: one sk_buff plus its data buffer is leaked per
malformed packet, unbounded. Note the drop counter is already incremented
for these errors, so the statistics claim a drop that never happens.

Three different ownership states reach out_frag: today - the skb may be
queued by the defrag engine (-EINPROGRESS), already freed by
nf_ct_handle_fragments(), or still owned by us. Tell the caller which of
those it is, and free the packet ourselves in the last case, which
restores the TC_ACT_SHOT behaviour that predated the Fixes: commit.

Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6
header with nexthdr = 0 (hop-by-hop) and nothing after it, on a
clsact ingress chain with "action ct". kmemleak reports one leaked
232-byte skbuff_head_cache object plus its 704-byte data buffer per
packet; with this patch it reports none.

Fixes: 3f14b377d0 ("net/sched: act_ct: fix skb leak and crash on ooo frags")
Cc: stable@vger.kernel.org # v6.8+
Signed-off-by: Hyunjung Ko <hj351016@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260806101235.809370-1-hj351016@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-10 16:37:07 -07:00
Hyunjung Ko
883b56ae58 net/sched: act_gact, act_police: range check the fallback control action
tcf_action_check_ctrlact() range checks the primary control action:

	if (!opcode)
		ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0;

TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it
cannot be set that way. But act_gact and act_police each carry a second,
independent control action supplied by user space that never reaches that
helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject
TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned
verbatim from the action.

In particular user space can store TC_ACT_CONSUMED, which is
TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value
range. That verdict tells every caller the action took ownership of the
skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for it. The result is
one leaked sk_buff plus its data buffer per packet traversing the filter,
unbounded, for all traffic on the chain including kernel-generated
packets.

Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so
with pval = 1 gact_determ() returns the fallback for every packet.
act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and
tcf_police_mtu_check() always passes.

TC_ACT_CONSUMED was added by commit 720f22fed8 ("net: sched: refactor
reinsert action"), after both goto-chain guards were written:
commit 9469f375ab ("net/sched: act_gact: disallow 'goto chain' on
fallback control action") and
commit c08f5ed5d6 ("net/sched: act_police: disallow 'goto chain' on
fallback control action"). Neither guard was widened when the new
verdict appeared.

Factor the existing range test out of tcf_action_check_ctrlact() as
tcf_action_valid() and apply it to both fallbacks. The helper cannot call
tcf_action_check_ctrlact() directly because that also allocates a
goto_chain, which is exactly what these two sites must not do.

Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte
skbuff_head_cache object plus its 704-byte data buffer per packet. With
this patch both configurations are rejected with -EINVAL and kmemleak
reports none.

Fixes: 720f22fed8 ("net: sched: refactor reinsert action")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Hyunjung Ko <hj351016@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-10 16:00:19 -07:00
Pablo Neira Ayuso
5546b082fa netfilter: add DEBUG_NET_WARN_ON_ONCE to skb_set_nfct()
Trigger a warning if nf_ct_set() overlaps an existing ct object leading
to refcount leak. Add this warning to skb_set_nfct() whose only user is
nf_ct_set() instead.

Update existing nf_ct_set() callers to use nf_reset_ct() first to clean
up stale pointer to conntrack object which migh trigger false positive
warnings.

Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-08-10 13:01:37 +02:00
Victor Nogueira
d4e359b360 net/sched: cls_api: fix teardown of an adopted proto on insert-race loss
In tc_new_tfilter() the create branch sets tp_created = 1 before calling
tcf_chain_tp_insert_unique(). When the caller loses the race (another
request inserted a proto at the same chain/prio first), insert_unique()
destroys the caller's own tp_new and returns the winner's proto with an
extra reference. tp_created was never cleared, so the loser's errout
path treated the winner's live proto as its own and called
tcf_chain_tp_delete_empty() on it, silently unlinking an active
classifier that the winning request already advertised via
RTM_NEWTFILTER.

Track the outcome of the insert step in a single tri-state variable so
each errout path reacts correctly:

- TP_NOT_CREATED: no proto created; pursue the old path.
- TP_CREATED: proto inserted successfully; same code path as before.
- TP_NOT_OWNED: New - lost the insert race; tp is another request's proto
  (chain ref already released by tp_new's destroy)

Both errout reactions are single expressions derived from the state.

This fix is motivated by the Sashiko's automated review of Patch
(net/sched: cls_api: Always acquire rtnl_lock when destroying locked
classifiers) [1][2]. The review identified the silent-unlink behaviour of
an adopted proto's teardown when a request loses the
tcf_chain_tp_insert_unique() race.

[1] https://sashiko.dev/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com
[2] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com

Fixes: 8b64678e0a ("net: sched: refactor tp insert/delete for concurrent execution")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com
Closes: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reported-by: TencentOS Corvus AI <corvus@tencent.com>
Tested-by: Aohan Mei <henrymei@tencent.com>
Link: https://patch.msgid.link/20260805134049.927864-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-07 17:22:12 -07:00
Jakub Kicinski
1962afd211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc7).

No conflicts, or adjacent changes.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-06 11:53:47 -07:00
Zijie Huang
dedd34b0f2 net/sched: reject overly deep qdisc hierarchies
Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
walkers and exhaust the kernel stack. The existing loop check does not
cover the create-and-graft path, so a hierarchy can still be extended by
creating a new child qdisc below an already deep parent.

Store the hierarchy depth in struct Qdisc and update it when qdiscs are
grafted. Reject new child qdiscs once the parent is already at the maximum
allowed depth.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reported-by: Vega <vega@nebusec.ai>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Zijie Huang <milkory@outlook.com>
Signed-off-by: Ren Wei <enjou1224z@gmail.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/1e9ab39597423fd5d13cfaaf52279b8ee3d9fc3c.1785434373.git.milkory@outlook.com
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-06 15:24:44 +02:00
Jamal Hadi Salim
a347304b2c net/sched: cls_api: Always acquire rtnl_lock when destroying locked classifiers
Another challenge with unlocked filters.
There is a short window in tc_new_tfilter where a tcf_proto can be found
and briefly referenced by a totally unrelated, unlocked classifier's request
and cause a race.

Feng created a poc which created this race with two threads, one creating a
u32 filter and other a flower filter in the same chain/prio:

1. Both threads enter tc_new_tfilter, both find the chain empty, both
   drop filter_chain_lock
2. u32 finishes tcf_proto_create("u32") first, calls
   tcf_chain_tp_insert_unique() -> inserts u32_tp into the chain
3. flower finishes tcf_proto_create("flower") later, calls
   tcf_chain_tp_insert_unique() -> tcf_chain_tp_find() now sees u32_tp
   already there, takes a reference on it, destroys flower's own tp_new
   and returns u32_tp to the caller.

Flower then hits the kind mismatch check (because it requested for kind
"flower" but tp->ops->kind is "u32") and goes through the errout path
which calls tcf_proto_put() on u32_tp. If the u32 thread has already
gone through its own errout (its change() call failed on the PoC's empty
options) and dropped its create and insert refs, flower's put is the
last one and drops u32_tp's refcnt to zero.

At this point tp->ops->destroy() runs in a context that never took
rtnl_lock. When that happens, it might cause a UAF like the following
(illustrated by the PoC):

[  +0.000710] BUG: KASAN: slab-use-after-free in u32_init (net/sched/cls_u32.c:393)
[  +0.000281] Read of size 8 at addr ffff888120022f00 by task poc_feng_xue/524

  Call Trace:
   u32_init (net/sched/cls_u32.c:393)
   tc_new_tfilter (net/sched/cls_api.c:2378)

  Allocated by task 526:
   u32_init (net/sched/cls_u32.c:378)
   tc_new_tfilter (net/sched/cls_api.c:2378)

  Freed by task 522:
   kfree
   u32_destroy (net/sched/cls_u32.c:662)
   tcf_proto_destroy (net/sched/cls_api.c:446)
   tcf_proto_put (net/sched/cls_api.c:459)
   tc_new_tfilter (net/sched/cls_api.c:2459)

Fix this by having tcf_proto_destroy() take rtnl_lock around
tp->ops->destroy() for locked classifiers whenever rtnl is not held.

To explain why I used a temp variable "not_lockless" I'd like to point to a
semi-related note on rtnl_held vs TCF_PROTO_OPS_DOIT_UNLOCKED (adding here
for future cleanup if deemed necessary):
The rtnl_held parameter and the TCF_PROTO_OPS_DOIT_UNLOCKED flag are
redundant sources of truth for whether rtnl_lock is held. Among the nine
classifier destroy(..rtnl_held..) callbacks, only flower consults the
rtnl_held parameter which it propagates to tc_setup_cb_destroy()
and tc_setup_cb_call(). The other eight (u32, flow, bpf, cgroup, route, basic,
fw, mall) ignore it entirely;-> those that call tc_setup_cb_destroy()
(u32, bpf, mall) hardcode true always instead of forwarding the parameter.

A future cleanup should remove the rtnl_held parameter from the destroy callback
signature entirely and have callers rely solely on their knowledge whether
they are running in an unlocked context.

Fixes: 12db03b65c ("net: sched: extend proto ops to support unlocked classifiers")
Reported-by: Feng Xue <feng.xue@outlook.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260801125632.360365-1-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-04 16:35:45 +02:00
Toke Høiland-Jørgensen
2a33516f9e net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter
The sch_cake ACK filter parses packets to find the TCP header and filter
duplicated ACKs if the flow is backlogged. The parsing code contains a
WARN_ON(1) which can be triggered by a malformed IP header in certain
cases. Depending on the system configuration, this leads either to
either spamming dmesg with warnings, or a panic if panic_on_warn is set.

The code already correctly skips the offending packet in the branch that
triggers the warning, so the WARN_ON itself doesn't really serve any
purpose. So just drop it altogether to avoid the inconvenient side
effects.

Fixes: 8b7138814f ("sch_cake: Add optional ACK filter")
Reported-by: Zhiling Zou <zhilinz@nebusec.ai>
Reported-by: Ren Wei <enjou1224z@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260729191417.45665-1-toke@toke.dk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-03 18:44:20 -07:00
Jamal Hadi Salim
47d7f70512 net/sched: cls_route: fix fastmap use-after-free on filter
The route4 classifier maintains a 16-slot fastmap cache that stores raw
struct route4_filter pointers indexed by (id, iif). The reader
(route4_classify) populates this cache via route4_set_fastmap() for every
classified packet that hits a filter. The writer (route4_delete,
route4_change) clears the cache via route4_reset_fastmap() before
RCU-deferred kfree of the filter.

This creates a UAF race:
 1. Reader walks the RCU-protected bucket chain, finds filter f
 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()
 3. Reader calls route4_set_fastmap() and writes f into the cache
    *after* the writer's reset, caching a pointer about to be freed
 4. After the RCU grace period, kfree(f) executes
 5. Next classified packet on the same (id, iif) tuple hits the stale
    fastmap entry and reads f->res from freed memory

Reproduced with an mdelay(100) accelerator in route4_set_fastmap() and a
concurrent add/delete stress test (provided by both zdi and Santosh).
Both triggered KASAN slab-use-after-free reports in the route4 fastmap
paths.

Fix:
Introduce a per-filter boolean dying flag to suppress stale fastmap
republishing by in-flight readers.

Fixes: 1109c00547 ("net: sched: RCU cls_route")
Reported-by: zdi-disclosures@trendmicro.com
Reported-by: Santosh Kalluri <santosh.kalluri129@gmail.com>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Tested-by: Santosh Kalluri <santosh.kalluri129@gmail.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260729094411.46257-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-31 17:26:40 -07:00
Jakub Kicinski
5c45807355 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc6).

No conflicts.

Adjacent changes:

net/ipv4/route.c
  dbc3791e3b ("net: do not send ICMP/NDISC Redirects when peer allocation fails")
  7804eaa057 ("ipv4: snapshot dst.dev in ip_rt_send_redirect() and ip_rt_get_source()")

drivers/net/tun.c
  23dad2d088 ("tun: no longer rely on RTNL in tun_fill_info()")
  c3da92af07 ("Revert "tun/tap: add ptr_ring consume helper with netdev queue wakeup"")

drivers/net/ethernet/marvell/octeontx2/af/rvu_npc.c
  3bd438a58e ("octeontx2-af: Block VFs from clobbering special CGX PKIND state")
  5ba5611ef9 ("octeontx2-af: reserve 4 PKINDs for skip-size custom use")

drivers/net/wireless/ath/ath12k/core.h
drivers/net/wireless/ath/ath12k/mac.c
drivers/net/wireless/ath/ath12k/peer.c
  469d7e6077 ("wifi: ath12k: resolve PENDING ML peer ID from MLO_PEER_MAP HTT event")
  378e659029 ("wifi: ath12k: introduce host_alloc_ml_id hardware parameter")
  c42b27336e ("wifi: ath12k: fix survey indexing across bands")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-30 12:53:19 -07:00
Cen Zhang (Microsoft)
aef96eead2 net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds
u32_change() copies the user-provided tc_u32_sel.offshift (unsigned char,
0-255) into the kernel knode object without bounds validation. When a
packet later hits u32_classify() with TC_U32_VAROFFSET set, it evaluates
`ntohs(offmask & *data) >> offshift` where the left operand is a 16-bit
value promoted to a 32-bit int. Any offshift >= 32 is undefined behavior
per C11 6.5.7p3, triggerable by an unprivileged user via user/network
namespaces.

UBSAN: shift-out-of-bounds in net/sched/cls_u32.c:236:43
shift exponent 32 is too large for 32-bit type int

Fix this by rejecting offshift >= 16 during filter creation in
u32_change().

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: AutonomousCodeSecurity@microsoft.com
Link: https://lore.kernel.org/all/20260720034514.23053-1-blbllhy@gmail.com
Signed-off-by: Cen Zhang (Microsoft) <blbllhy@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260723044955.89471-1-blbllhy@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-28 11:18:58 +02:00
Jonas Köppeler
a3729e0df0 net/sched: sch_cake: skip clearing unused tins during rate adjustment
When cake_configure_rates() is called from the dequeue path with
rate_adjust=true, it only needs to update the rate parameters. The
loop that clears the unused tins is both unnecessary and harmful in
this path:

 - cake_clear_tin() overwrites q->cur_tin and q->cur_flow, which are
   actively used by cake_dequeue(), corrupting the dequeue state.
 - iterating over the unused tins and their internal queues to purge
   packets adds needless overhead to the hot path.

Skip the entire loop when rate_adjust is set, as neither
cake_clear_tin() nor the mtu_time update are needed when only the
rate changes.

The clearing loop runs on every rate adjustment from the dequeue path,
clearing (max_tins - cur_tins) tins each time, so the cost grows the
fewer tins the configured mode actually uses. Testing cake_mq over veth
(8 rx/tx queues, 2 Gbit limit) with flent's [1] rrul and tcp_nup tests and
32 TCP upstreams shows a large drop in loaded latency and a throughput
gain, restoring behaviour to pre-15c2715a5264 levels:

  +------------+------+------+-------+-------+---------+
  | kernel     | mode | test |  base |  load |    tput |
  |            |      |      |  (ms) |  (ms) |  (Mbit) |
  +------------+------+------+-------+-------+---------+
  | net-next   | be   | rrul | 0.810 | 11.78 | 1469.67 |
  | net-next   | be   | nup  | 0.637 | 85.71 | 1243.15 |
  | net-next   | ds3  | rrul | 0.397 | 15.28 | 1770.06 |
  | net-next   | ds3  | nup  | 0.351 | 15.98 | 1799.39 |
  +------------+------+------+-------+-------+---------+
  | patched    | be   | rrul | 0.092 |  0.56 | 1873.40 |
  | patched    | be   | nup  | 0.109 |  1.82 | 1869.12 |
  | patched    | ds3  | rrul | 0.097 |  0.98 | 1866.10 |
  | patched    | ds3  | nup  | 0.101 |  0.51 | 1861.79 |
  +------------+------+------+-------+-------+---------+

The same trend holds on real hardware (IPQ8074A, 4 rx/tx queues,
OpenWrt): in besteffort mode the tcp_nup loaded latency drops from
~470 ms to ~4 ms.

[1] https://flent.org

Fixes: 15c2715a52 ("net/sched: sch_cake: fixup cake_mq rate adjustment for diffserv config")
Signed-off-by: Jonas Köppeler <j.koeppeler@tu-berlin.de>
Tested-by: Mike Pham <mikepham4321@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260720-sch_cake-skip-clearing-tins-v2-1-e6a8b0275c73@tu-berlin.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-24 16:26:51 -07:00
Jakub Kicinski
89d8006259 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc5).

Conflicts:

drivers/net/amt.c
  3656a79f94 ("amt: re-read skb header pointers after every pull")
  586c4dcf28 ("amt: no longer rely on RTNL in amt_fill_info()")
https://lore.kernel.org/amIaJr3aOQNS_Fvl@sirena.org.uk

Adjacent changes:

drivers/net/geneve.c
  8efb8f8bbb ("geneve: require CAP_NET_ADMIN in the device netns for changelink")
  0ba269933f ("geneve: convert config to RCU-protected pointer")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23 14:07:40 -07:00
Aldo Ariel Panzardo
f43ee0c073 net/sched: serialize qdisc_rtab_list against concurrent get/put
qdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly
linked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no
lock. This was only safe because every caller historically held the RTNL
mutex, which serialized all rate-table lookups, inserts and frees.

That invariant no longer holds. cls_flower sets
TCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false
for it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through
tcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() ->
tcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the
RTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each
adding a flower filter with a police action carrying the same rate, then
race on qdisc_rtab_list and on the non-atomic refcnt, leading to a
use-after-free / double-free of the kmalloc-2k struct qdisc_rate_table.
qdisc_rtab_list is a single global (not per-netns), so the corrupted
object is shared system-wide.

  BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160
   qdisc_put_rtab+0x12f/0x160
   tcf_police_init+0xda9/0x1590
   tcf_action_init_1+0x460/0x6b0
   tcf_action_init+0x439/0xa40
   tcf_exts_validate_ex+0x42d/0x550
   fl_change+0xddd/0x7da0
   tc_new_tfilter+0xaa7/0x2420
   rtnetlink_rcv_msg+0x95e/0xe90
  which belongs to the cache kmalloc-2k of size 2048

Protect qdisc_rtab_list and the refcount with a dedicated spinlock. The
(sleeping, GFP_KERNEL) allocation in qdisc_get_rtab() is performed before
taking the lock; if a concurrent inserter added an identical table in the
meantime the freshly allocated one is freed under the lock, so no
duplicate is leaked. qdisc_put_rtab() now decrements the refcount and
unlinks under the same lock.

Fixes: 470502de5b ("net: sched: unlock rules update API")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Aldo Ariel Panzardo <qwe.aldo@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260715114114.446841-1-qwe.aldo@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-22 15:07:53 -07:00
Paolo Abeni
4d3365d5d3 Merge branch 'big-tcp-for-udp-tunnels'
Alice Mikityanska says:

====================
BIG TCP for UDP tunnels

This series is a follow-up to "BIG TCP without HBH in IPv6", and it adds
support for BIG TCP IPv4/IPv6 workloads in vxlan and geneve. Now that
IPv6 BIG TCP doesn't require stripping the HBH in all various
combinations in tunneled traffic, adding BIG TCP becomes feasible.

Patch 01 adds accessors for the length field in the UDP header, as
suggested by Paolo in review. The usage of udp_set_len is then added in
the following patches that start using length=0 in BIG TCP UDP packets.

Patches 02-04 close the gaps that prevent BIG TCP packets from going
through UDP tunnel code.

Patch 05 validates packets in udp_gro_receive to exclude packets with
length=0 from GRO aggregation.

Patch 06 is for proper formatting in tcpdump (set UDP len to 0 rather
than a trimmed value on overflow).

Patches 07-08 bump up tso_max_size for VXLAN and GENEVE.

Patch 09 adds selftests.
====================$

Link: https://patch.msgid.link/20260710134242.216538-1-alice.kernel@fastmail.im
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-22 13:49:03 +02:00
Alice Mikityanska
5329647dad net: Use helpers to get/set UDP len tree-wide
Since BIG TCP for UDP tunnels will start using len=0 in the UDP header
as an indicator of a GSO packet bigger than 65535 bytes, this commit
introduces the following getter and setters to use tree-wide, in order
to explicitly mark places where len=0 may be expected, and handle them
properly:

1. udp_set_len() sets uh->len to its real value if it's not bigger than
65535, and to 0 otherwise: to be used in GSO context with aggregated
packets.

2. udp_set_len_short() is to be used when the length is known to fit 16
bits. It WARNs when the caller tries to assign a bigger value if
CONFIG_DEBUG_NET=y.

3. udp_get_len_short() returns len in host byte order: to be used on the
RX side to deal with non-aggregated packets, or to access the raw value
of the len field.

4. udp_get_len() decodes uh->len set by udp_set_len(). It checks whether
the packet is GSO to guard from malformed packets.

At the moment udp_set_len() is not used, a following commit will start
using it after enabling len>65535 for GSO.

Raw uh->len (in network byte order) is still accessed in a few places
for checksum calculation purposes, and to decode len=0 in udpv6_rcv for
jumbograms. udp_rcv and udpv6_rcv will be addressed by the commit that
starts using udp_set_len() to set UDP len=0 for BIG TCP packets in UDP
tunnels.

Signed-off-by: Alice Mikityanska <alice@isovalent.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://patch.msgid.link/20260710134242.216538-2-alice.kernel@fastmail.im
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-22 13:47:02 +02:00
Jamal Hadi Salim
ec48b3be2c net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains
When a TC filter attached to a qdisc filter chain returns
TC_ACT_REDIRECT (ex: via an eBPF program calling bpf_redirect() or an
act_bpf action), the redirect was silently lost i.e no qdisc classify
function handled TC_ACT_REDIRECT, so the packet fell through the
switch and was enqueued normally instead of being redirected.

This has been broken since bpf_redirect() was introduced for TC in
commit 27b29f6305 ("bpf: add bpf_redirect() helper"). We got lucky
for a long time because bpf_net_context was a per-CPU variable that
was always available.

commit 401cb7dae8 ("net: Reference bpf_redirect_info via task_struct
on PREEMPT_RT.") turned bpf_net_context into a task_struct member that
is only set up by explicit callers. Without a caller setting it up,
bpf_redirect() itself crashes with a NULL pointer dereference in
bpf_net_ctx_get_ri(). However, even with bpf_net_context available,
TC_ACT_REDIRECT from qdisc filter chains cannot be honored without
adding skb_do_redirect() calls to every qdisc classify function, which
would require changes across net/sched/. Isolate it to ebpf core where
it belongs.

Instead, add a tcf_classify_qdisc() inline helper in pkt_cls.h, as a
wrapper around tcf_classify() for use by qdisc classify functions and
tcf_qevent_handle(). When the classify verdict is TC_ACT_REDIRECT,
the wrapper converts it to TC_ACT_SHOT, dropping the packet rather
than letting it continue silently. Dropping is preferred over
letting the packet through because the user immediately sees packet
loss. Silently passing the packet through would hide the problem and
leave the user wondering why their redirect is not working.

The clsact fast path, tc_run() continues to call tcf_classify() directly
and is unaffected: TC_ACT_REDIRECT is returned as-is and handled by
sch_handle_egress/ingress() calling skb_do_redirect() as before.

Fixes: 27b29f6305 ("bpf: add bpf_redirect() helper")
Fixes: 401cb7dae8 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260706185609.330006-3-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-20 18:16:43 -07:00
Daniel Borkmann
3f4920d165 bpf: Reject redirect helpers without a bpf_net_context
The bpf_redirect*() helpers and skb_do_redirect() obtain the per-task
bpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the
current->bpf_net_context unconditionally. That context is established
on the paths that run tc BPF such as sch_handle_{ingress,egress}(),
*except* for the case where {cls,act}_bpf was attached to a proper
qdisc. A program running from there reaches the NULL deref in two ways:

* It calls bpf_redirect() directly, which dereferences the context at
  the top of the helper:

     tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \
        avpkt 1000 burst 100 qevent early_drop block 10
     tc filter add block 10 pref 1 bpf obj redirect.o

* It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle()
  then dispatches to skb_do_redirect(), which dereferences the context

Rather than extending bpf_net_context management into the qdisc path,
make the redirect helpers refuse to operate when no context exists, and
have tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of
calling skb_do_redirect(). Previous behaviour was a crash, so nothing
regresses by not supporting it.

Fixes: 401cb7dae8 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
Fixes: 3625750f05 ("net: sched: Introduce helpers for qevent blocks")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260706185609.330006-2-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-20 18:16:42 -07:00
Paolo Abeni
298bb2b890 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc4).

No conflicts.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-20 09:18:11 +02:00
Jamal Hadi Salim
f1f5c8a395 net/sched: act_tunnel_key: Defer dst_release to RCU callback
Fix a race-condition use-after-free in tunnel_key_release_params().

The function releases the metadata_dst of the old params synchronously
via dst_release() while deferring the params struct free with
kfree_rcu(). A concurrent tunnel_key_act() reader on the datapath may
still hold the old params pointer (under rcu_read_lock_bh) and proceed
to call dst_clone(&params->tcft_enc_metadata->dst) after the writer's
dst_release has already pushed the dst's rcuref to RCUREF_DEAD.

zdi-disclosures@trendmicro.com produced a poc which i (and Victor) verified
that KASAN reports:

==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112
BUG: KASAN: slab-use-after-free in atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326
BUG: KASAN: slab-use-after-free in __rcuref_put include/linux/rcuref.h:109
BUG: KASAN: slab-use-after-free in rcuref_put include/linux/rcuref.h:173
BUG: KASAN: slab-use-after-free in dst_release+0x5b/0x370 net/core/dst.c:168
Write of size 4 at addr ffff88806158de40 by task poc/9388

CPU: 0 UID: 0 PID: 9388 Comm: poc Tainted: G        W           7.1.0-rc7 #7 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378
 print_report+0x139/0x4ad mm/kasan/report.c:482
 kasan_report+0xe4/0x1d0 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:186
 kasan_check_range+0x125/0x200 mm/kasan/generic.c:200
 instrument_atomic_read_write include/linux/instrumented.h:112
 atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326
 __rcuref_put include/linux/rcuref.h:109
 rcuref_put include/linux/rcuref.h:173
 dst_release+0x5b/0x370 net/core/dst.c:168
 refdst_drop include/net/dst.h:272
 skb_dst_drop include/net/dst.h:284
 skb_release_head_state+0x293/0x400 net/core/skbuff.c:1163
 skb_release_all net/core/skbuff.c:1187
[..]
Allocated by task 9391:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398
 __kasan_kmalloc+0x9a/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263
 __do_kmalloc_node mm/slub.c:5296
 __kmalloc_noprof+0x2f1/0x830 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954
 kzalloc_noprof include/linux/slab.h:1188
 offload_action_alloc+0x2f/0x130 net/core/flow_offload.c:35
 tcf_action_offload_add_ex+0x1ba/0x880 net/sched/act_api.c:258
 tcf_action_offload_add net/sched/act_api.c:293
 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547
 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101
[..]
Freed by task 9391:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253
 __kasan_slab_free+0x6b/0x90 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235
 slab_free_hook mm/slub.c:2689
 slab_free mm/slub.c:6251
 kfree+0x21f/0x6b0 mm/slub.c:6566
 tcf_action_offload_add_ex+0x4ad/0x880 net/sched/act_api.c:284
 tcf_action_offload_add net/sched/act_api.c:293
 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547
 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101

The buggy address belongs to the object at ffff88806158de00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 64 bytes inside of
 freed 256-byte region [ffff88806158de00, ffff88806158df00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806158d600 pfn:0x6158c
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000240(workingset|head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000240 ffff88801c841b40 ffffea0001856290 ffffea0001856190
raw: ffff88806158d600 0000000800100009 00000000f5000000 0000000000000000
head: 04fff00000000240 ffff88801c841b40 ffffea0001856290 ffffea0001856190
head: ffff88806158d600 0000000800100009 00000000f5000000 0000000000000000
head: 04fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 9391, tgid 9378 (poc), ts 123227323196, free_ts 0
 set_page_owner include/linux/page_owner.h:32
 post_alloc_hook+0xfe/0x140 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861
 get_page_from_freelist+0x110c/0x2fc0 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x263/0x2bc0 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278
 allocate_slab mm/slub.c:3467
 new_slab+0xa6/0x690 mm/slub.c:3525
 refill_objects+0x271/0x420 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816
 __pcs_replace_empty_main+0x373/0x630 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750
 slab_alloc_node mm/slub.c:4884
 __do_kmalloc_node mm/slub.c:5295
 __kmalloc_noprof+0x66d/0x830 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954
 metadata_dst_alloc+0x26/0x90 net/core/dst.c:298
 tun_rx_dst include/net/dst_metadata.h:144
 __ip_tun_set_dst include/net/dst_metadata.h:208
 tunnel_key_init+0xb01/0x1b90 net/sched/act_tunnel_key.c:451
 tcf_action_init_1+0x46b/0x6c0 net/sched/act_api.c:1428
 tcf_action_init+0x448/0xa20 net/sched/act_api.c:1503
 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101
[..]
==================================================================

Fix by moving dst_release() into a custom RCU callback that runs
after the grace period, matching the lifetime of the containing
params struct.  Readers in the datapath therefore always find a live
rcuref when calling dst_clone().

Fixes: 9174c3df1c ("net/sched: act_tunnel_key: fix memory leak in case of action replace")
Reported-by: zdi-disclosures@trendmicro.com
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20260711150537.7946-1-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-17 12:13:20 +02:00
Paolo Abeni
b470fde8f7 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-7.2-rc3).

Conflicts:

tools/testing/selftests/net/lib.sh
  dd6a23bac3 ("selftests: net: make busywait timeout clock portable")
  895bad9cc4 ("selftests: net: make busywait timeout clock portable")

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-10 10:20:05 +02:00
Samuel Moelius
b7f97cae7e net/sched: cake: reject overhead values that underflow length
CAKE accepts signed overhead values and stores them in an s16, but the
adjusted packet length calculation uses unsigned arithmetic.  A negative
effective length can therefore wrap to a large value.

Such configurations make rate accounting depend on integer wraparound
rather than on the packet size userspace intended to model.  A static
netlink lower bound is not enough because packets reaching CAKE can be
smaller than any reasonable manual-overhead allowance.

Fold the signed overhead adjustment into the existing datapath MPU clamp
so negative adjusted lengths are clamped before link-layer framing
adjustments.

Fixes: a729b7f0bd ("sch_cake: Add overhead compensation support to the rate shaper")
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260702000758.297407.e5c888d9d99d.cake-overhead-underflow@trailofbits.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-08 11:42:21 +02:00
Jamal Hadi Salim
8b519cbcab net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload
There is a TOCTOU race condition in flower lockless approach between sizing
a flow_rule buffer and filling it.
zdi-disclosures@trendmicro.com reports:
The cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED
(fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the
independent locking domains make the race reachable in practice.  KASAN
confirms:
  BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930
  Write of size 4 at addr ffff888001f27520 by task poc-toctou/312
  The buggy address is located 0 bytes to the right of
   allocated 288-byte region [ffff888001f27400, ffff888001f27520)
   (cache kmalloc-512)

Note: The result is a heap OOB write attacker-controlled content into the
adjacent slab object (requires CAP_NET_ADMIN).

The fix introduces reading tcfp_nkeys under act->tcfa_lock in all places
using a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys().
Additionally we close the remaining TOCTOU window between the sizing read and
the fill reads by more careful accounting.
Rather than silently truncating the key count, which leads to incorrect
action semantics offloaded to hardware and secondary OOB writes if
the remaining capacity is zero or consumed by prior actions, we enforce
remaining capacity checks and return -ENOSPC if the required space exceeds
the remaining capacity.

Fixes: 71d0ed7079 ("net/act_pedit: Support using offset relative to the conventional network headers")
Reported-by: zdi-disclosures@trendmicro.com
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260701161912.125355-1-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-06 12:52:01 +02:00
Paolo Abeni
b73bc9ca36 netfilter pull request nf-next-26-07-02
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Merge tag 'nf-next-26-07-02' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next

Florian Westphal says:

====================
netfilter: updates for net-next

The following patchset contains Netfilter updates for *net-next*.

1) Update nfnetlink_hook to dump the individual NAT type chains
instead of the nat base chains to userspace. From Phil Sutter.

2) Replace strlcpy/strlcat() with snprintf() in x_tables, from Ian Bridges.

3) Start replacing u_int8_t and u_int16t with u8 and u16 in netfilter.
From Carlos Grillet.

4) Replace strcpy() with strscpy() in netfilter, from David Laight.

5) Remove redundant NULL check before kvfree().

6) Add parameter validation to xt_tcpmss. Ensure mss_min <= mss_max and
invert <= 1.  From Feng Wu.

7) Add checkentry for xt_dscp 'tos' match. Implement tos_mt_check() to reject
invalid invert values.  Also from Feng Wu.

8) Stop hashing nf_conntrack_helper by tuple. Switch to hashing by name and
L4 protocol.

9) Remove tuples from conntrack helper definitions and port usage from
broadcast helpers. Add netlink policy validation to prevent protocol
number truncation.

10) Remove obsolete netfilter conntrack module parameters.

11) Bound num_counters in ebtables: do_replace() by MAX_EBT_ENTRIES to prevent
oversized vmalloc_array() allocations.  From Jiayuan Chen.

12) Make expectations created via nft_ct rules work with NAT.

netfilter pull request nf-next-26-07-02

* tag 'nf-next-26-07-02' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: nft_ct: support expectation creation for natted flows
  netfilter: ebtables: bound num_counters like nentries in do_replace()
  netfilter: conntrack: remove obsolete module parameters
  netfilter: conntrack: get rid of tuple in helper definitions
  netfilter: nf_conntrack_helper: do not hash by tuple
  netfilter: xt_dscp: add checkentry for tos match
  netfilter: xt_tcpmss: add checkentry for parameter validation
  netfilter: remove redundant null check before kvfree()
  netfilter: avoid strcpy usage
  netfilter: replace u_int8_t and u_int16t with u8 and u16
  netfilter: x_tables: replace strlcat() with snprintf()
  netfilter: nfnetlink_hook: Dump nat type chains
====================

Link: https://patch.msgid.link/20260702105003.13550-1-fw@strlen.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-03 22:00:24 +02:00
Jamal Hadi Salim
6301f6a34e net/sched: sch_teql: move rcu_read_lock()/spin_lock() from _bh variants
This is a followup based on sashiko comments [1] on commit e5b811fe79
("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF")

Use plain rcu_read_lock()/spin_lock() in teql_master_xmit() instead of the
_bh variants, since ndo_start_xmit is already invoked with BH disabled
by the core stack and the _bh primitives can warn in_hardirq() when xmit
is reached through netpoll or a softirq xmit path with hard IRQs disabled.

Moves rcu_read_lock() after restart: label + adds rcu_read_unlock() before
goto restart (fixes the unbounded RCU hold across retries)

[1] https://sashiko.dev/#/patchset/20260628111229.669751-1-jhs%40mojatatu.com

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Fixes: e5b811fe79 ("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF")
Link: https://patch.msgid.link/20260630150922.238714-1-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-03 16:02:38 +02:00