mirror of
https://github.com/torvalds/linux.git
synced 2026-07-28 10:09:10 +02:00
320fb29ea2
During a reset, CBS is not calling reset on its child qdisc, which
might cause qlen/backlog accounting issues. For example, if we have CBS
with a QFQ parent and a netem child with delay, we can create a scenario
where the parent's qlen underflows. QFQ, specifically, uses qlen to
check whether it should deference a pointer, so this scenario may cause
a null-ptr deref in QFQ:
[ 43.875639][ T319] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI
[ 43.876124][ T319] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
[ 43.876417][ T319] CPU: 10 UID: 0 PID: 319 Comm: ping Not tainted 7.0.0-13039-ge728258debd5 #773 PREEMPT(full)
[ 43.876751][ T319] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 43.876949][ T319] RIP: 0010:qfq_dequeue+0x35c/0x1650
[ 43.877123][ T319] Code: 00 fc ff df 80 3c 02 00 0f 85 17 0e 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 76 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b
[ 43.877648][ T319] RSP: 0018:ffff8881017ef4f0 EFLAGS: 00010216
[ 43.877845][ T319] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000
[ 43.878073][ T319] RDX: 0000000000000009 RSI: 0000000c40000000 RDI: ffff88810eef02b0
[ 43.878306][ T319] RBP: ffff88810eef0000 R08: ffff88810eef0280 R09: 1ffff1102120fd63
[ 43.878523][ T319] R10: 1ffff1102120fd66 R11: 1ffff1102120fd67 R12: 0000000c40000000
[ 43.878742][ T319] R13: ffff88810eef02b8 R14: 0000000000000048 R15: 0000000020000000
[ 43.878959][ T319] FS: 00007f9c51c47c40(0000) GS:ffff88817a0be000(0000) knlGS:0000000000000000
[ 43.879214][ T319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 43.879403][ T319] CR2: 000055e69a2230a8 CR3: 000000010c07a000 CR4: 0000000000750ef0
[ 43.879621][ T319] PKRU: 55555554
[ 43.879735][ T319] Call Trace:
[ 43.879844][ T319] <TASK>
[ 43.879924][ T319] __qdisc_run+0x169/0x1900
[ 43.880075][ T319] ? dev_qdisc_enqueue+0x8b/0x210
[ 43.880222][ T319] __dev_queue_xmit+0x2346/0x37a0
[ 43.880376][ T319] ? register_lock_class+0x3f/0x800
[ 43.880531][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.880684][ T319] ? __pfx___dev_queue_xmit+0x10/0x10
[ 43.880834][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.880977][ T319] ? __lock_acquire+0x819/0x1df0
[ 43.881124][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.881275][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.881418][ T319] ? __asan_memcpy+0x3c/0x60
[ 43.881563][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.881708][ T319] ? eth_header+0x165/0x1a0
[ 43.881853][ T319] ? lockdep_hardirqs_on_prepare+0xdb/0x1a0
[ 43.882031][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.882174][ T319] ? neigh_resolve_output+0x3cc/0x7e0
[ 43.882325][ T319] ? srso_alias_return_thunk+0x5/0xfbef5
[ 43.882471][ T319] ip_finish_output2+0x6b6/0x1e10
Fix this by calling qdisc_reset for CBS' child qdisc.
Sashiko caught an issue which could result in a null ptr deref if
qdisc_create_dflt() is invoked on an unitialised cbs qdisc which is exposed
by this patch. We add an early return if the qdisc is null to address this.
This is a similar approach used by two other fixes[1][2].
The proper fix for this specific issue elucidated by sashiko is to remove
the call to qdisc_reset when qdisc_create_dflt fails. Since the dflt qdisc
isn't attached anywhere yet at that point, calling the reset callback doesn't
make much sense (and as stated has been a source of two other bugs).
We plan on submitting this fix in a later patch.
[1] https://lore.kernel.org/netdev/20221018063201.306474-2-shaozhengchao@huawei.com/
[2] https://lore.kernel.org/netdev/20221018063201.306474-4-shaozhengchao@huawei.com/
Fixes:
|
||
|---|---|---|
| .. | ||
| act_api.c | ||
| act_bpf.c | ||
| act_connmark.c | ||
| act_csum.c | ||
| act_ct.c | ||
| act_ctinfo.c | ||
| act_gact.c | ||
| act_gate.c | ||
| act_ife.c | ||
| act_meta_mark.c | ||
| act_meta_skbprio.c | ||
| act_meta_skbtcindex.c | ||
| act_mirred.c | ||
| act_mpls.c | ||
| act_nat.c | ||
| act_pedit.c | ||
| act_police.c | ||
| act_sample.c | ||
| act_simple.c | ||
| act_skbedit.c | ||
| act_skbmod.c | ||
| act_tunnel_key.c | ||
| act_vlan.c | ||
| bpf_qdisc.c | ||
| cls_api.c | ||
| cls_basic.c | ||
| cls_bpf.c | ||
| cls_cgroup.c | ||
| cls_flow.c | ||
| cls_flower.c | ||
| cls_fw.c | ||
| cls_matchall.c | ||
| cls_route.c | ||
| cls_u32.c | ||
| em_canid.c | ||
| em_cmp.c | ||
| em_ipset.c | ||
| em_ipt.c | ||
| em_meta.c | ||
| em_nbyte.c | ||
| em_text.c | ||
| em_u32.c | ||
| ematch.c | ||
| Kconfig | ||
| Makefile | ||
| sch_api.c | ||
| sch_blackhole.c | ||
| sch_cake.c | ||
| sch_cbs.c | ||
| sch_choke.c | ||
| sch_codel.c | ||
| sch_drr.c | ||
| sch_dualpi2.c | ||
| sch_etf.c | ||
| sch_ets.c | ||
| sch_fifo.c | ||
| sch_fq_codel.c | ||
| sch_fq_pie.c | ||
| sch_fq.c | ||
| sch_frag.c | ||
| sch_generic.c | ||
| sch_gred.c | ||
| sch_hfsc.c | ||
| sch_hhf.c | ||
| sch_htb.c | ||
| sch_ingress.c | ||
| sch_mq.c | ||
| sch_mqprio_lib.c | ||
| sch_mqprio_lib.h | ||
| sch_mqprio.c | ||
| sch_multiq.c | ||
| sch_netem.c | ||
| sch_pie.c | ||
| sch_plug.c | ||
| sch_prio.c | ||
| sch_qfq.c | ||
| sch_red.c | ||
| sch_sfb.c | ||
| sch_sfq.c | ||
| sch_skbprio.c | ||
| sch_taprio.c | ||
| sch_tbf.c | ||
| sch_teql.c | ||