Eyal Birger 9ef33d23f8 bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook ... [ Upstream commit b02d196c44 ] xmit_check_hhlen() observes the dst for getting the device hard header length to make sure a modified packet can fit. When a helper which changes the dst - such as bpf_skb_set_tunnel_key() - is called as part of the xmit program the accessed dst is no longer valid. This leads to the following splat: BUG: kernel NULL pointer dereference, address: 00000000000000de #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 798 Comm: ping Not tainted 5.18.0-rc2+ #103 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 RIP: 0010:bpf_xmit+0xfb/0x17f Code: c6 c0 4d cd 8e 48 c7 c7 7d 33 f0 8e e8 42 09 fb ff 48 8b 45 58 48 8b 95 c8 00 00 00 48 2b 95 c0 00 00 00 48 83 e0 fe 48 8b 00 <0f> b7 80 de 00 00 00 39 c2 73 22 29 d0 b9 20 0a 00 00 31 d2 48 89 RSP: 0018:ffffb148c0bc7b98 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000240008 RCX: 0000000000000000 RDX: 0000000000000010 RSI: 00000000ffffffea RDI: 00000000ffffffff RBP: ffff922a828a4e00 R08: ffffffff8f1350e8 R09: 00000000ffffdfff R10: ffffffff8f055100 R11: ffffffff8f105100 R12: 0000000000000000 R13: ffff922a828a4e00 R14: 0000000000000040 R15: 0000000000000000 FS: 00007f414e8f0080(0000) GS:ffff922afdc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000de CR3: 0000000002d80006 CR4: 0000000000370ef0 Call Trace: <TASK> lwtunnel_xmit.cold+0x71/0xc8 ip_finish_output2+0x279/0x520 ? __ip_finish_output.part.0+0x21/0x130 Fix by fetching the device hard header length before running the BPF code. Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure") Signed-off-by: Eyal Birger <eyal.birger@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220420165219.1755407-1-eyal.birger@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-05-09 09:05:02 +02:00
..
bpf_sk_storage.c
datagram.c
datagram.h
dev_addr_lists.c
dev_ioctl.c
dev.c	xdp: check prog type before updating BPF link	2022-01-27 10:54:30 +01:00
devlink.c	devlink: Remove misleading internal_flags from health reporter dump	2022-01-27 10:54:34 +01:00
drop_monitor.c	drop_monitor: fix data-race in dropmon_net_event / trace_napi_poll_hit	2022-02-23 12:01:02 +01:00
dst_cache.c	wireguard: device: reset peer src endpoint when netns exits	2021-12-08 09:03:22 +01:00
dst.c
failover.c
fib_notifier.c
fib_rules.c	ipv6: fix memory leak in fib6_rule_suppress	2021-12-08 09:03:21 +01:00
filter.c	bpf: Support dual-stack sockets in bpf_tcp_check_syncookie	2022-04-13 21:01:06 +02:00
flow_dissector.c	net/sched: flower: fix parsing of ethertype following VLAN header	2022-04-20 09:23:11 +02:00
flow_offload.c
gen_estimator.c
gen_stats.c
gro_cells.c
hwbm.c
link_watch.c
lwt_bpf.c	bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook	2022-05-09 09:05:02 +02:00
lwtunnel.c	lwtunnel: Validate RTA_ENCAP_TYPE attribute length	2022-01-11 15:25:00 +01:00
Makefile
neighbour.c	net, neigh: clear whole pneigh_entry at alloc time	2021-12-14 11:32:43 +01:00
net_namespace.c	netns: add schedule point in ops_exit_list()	2022-01-27 10:54:33 +01:00
net-procfs.c	net-procfs: show net devices bound packet types	2022-02-01 17:25:44 +01:00
net-sysfs.c	net-sysfs: add check for netdevice being present to speed_show	2022-03-16 14:16:00 +01:00
net-sysfs.h
net-traces.c
netclassid_cgroup.c
netevent.c
netpoll.c
netprio_cgroup.c
page_pool.c
pktgen.c
ptp_classifier.c
request_sock.c
rtnetlink.c	net: limit altnames to 64k total	2022-04-13 21:01:00 +02:00
scm.c
secure_seq.c
skbuff.c	net: fix up skbs delta_truesize in UDP GRO frag_list	2022-03-08 19:09:32 +01:00
skmsg.c	bpf, sockmap: Fix memleak in tcp_bpf_sendmsg while sk msg is full	2022-04-08 14:40:21 +02:00
sock_diag.c
sock_map.c	bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc	2021-12-17 10:14:41 +01:00
sock_reuseport.c
sock.c	sock: fix /proc/net/sockstat underflow in sk_clone_lock()	2021-11-26 10:39:14 +01:00
stream.c	net: stream: don't purge sk_error_queue in sk_stream_kill_queues()	2021-11-18 14:04:08 +01:00
sysctl_net_core.c	bpf: Prevent increasing bpf_jit_limit above max	2021-11-18 14:03:42 +01:00
timestamping.c
tso.c
utils.c
xdp.c