net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74267
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:22:26 UTC
Updated2026-08-17 06:19:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen Whenever codel drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though codel still has 1 packet on the queue and, thus, will mistakenly deactivate the parent's class causing issues like a wild memory access when qfq has codel as a child: [ 36.339843][ T370] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI [ 36.340408][ T370] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127] [ 36.340737][ T370] CPU: 2 UID: 0 PID: 370 Comm: tc Not tainted 7.1.0-rc5-00287-g66e13b626592 #87 PREEMPT(full) [ 36.341113][ T370] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 36.341357][ T370] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:1029 (discriminator 2) include/linux/list.h:1043 (discriminator 2) net/sched/sch_qfq.c:1369 (discriminator 2) net/sched/sch_qfq.c:1395 (discriminator 2)) sch_qfq [ 36.342221][ T370] RSP: 0018:ffff8881100ef370 EFLAGS: 00010216 [ 36.342422][ T370] RAX: 0000000000000000 RBX: ffff8881058a9568 RCX: dffffc0000000000 [ 36.342664][ T370] RDX: 1ffff11021064dc3 RSI: ffff888108326e00 RDI: dffffc0000000000 [ 36.342905][ T370] RBP: ffff8881058a8280 R08: dead000000000122 R09: 1bd5a00000000024 [ 36.343140][ T370] R10: fffffbfff2940329 R11: fffffbfff2940329 R12: 0000000000000000 [ 36.343383][ T370] R13: dead000000000100 R14: ffff8881058a9580 R15: ffff8881058a9578 [ 36.343631][ T370] FS: 00007fc04b0ca780(0000) GS:ffff888184fef000(0000) knlGS:0000000000000000 [ 36.343911][ T370] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.344116][ T370] CR2: 0000557c02c02000 CR3: 000000010e0ba000 CR4: 0000000000750ef0 [ 36.344359][ T370] PKRU: 55555554 [ 36.344481][ T370] Call Trace: ... [ 36.345054][ T370] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq [ 36.345222][ T370] qdisc_reset (net/sched/sch_generic.c:1057) [ 36.345503][ T370] __qdisc_destroy (net/sched/sch_generic.c:1096) [ 36.345677][ T370] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159) [ 36.346335][ T370] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.007040000 probability, percentile 0.502730000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected cc71a757da78dd4aa1b4a9b19cb011833730ccf2 bb9cfd874ee884117b33e92a002b9a45b48202f4 git Not specified
CNA Linux Linux affected eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450 7a05af7f58566682b73578b72ca8e53a268c43bd git Not specified
CNA Linux Linux affected 829c49b6b2ff45b043739168fd1245e4e1a91a30 eba49fd85995a3851c597fa2d214f8d21736e1d8 git Not specified
CNA Linux Linux affected 2f9761a94bae33d26e6a81b31b36e7d776d93dc1 e8c6dbadf139cb14ea6ed14add6ed6e88504dedd git Not specified
CNA Linux Linux affected 4d55144b12e742404bb3f8fee6038bafbf45619d e4615aa6bb7802944ae790cb4b3ef8c1b7491af3 git Not specified
CNA Linux Linux affected 342debc12183b51773b3345ba267e9263bdfaaef 755108bb7a5083e911294c416cfea605dc75632f git Not specified
CNA Linux Linux affected 342debc12183b51773b3345ba267e9263bdfaaef 91e0a793a72374c20ab31a40ccec21373e82e973 git Not specified
CNA Linux Linux affected 342debc12183b51773b3345ba267e9263bdfaaef 52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3 git Not specified
CNA Linux Linux affected 7a742a9506849d1c1aa71e36c89855ceddc7d58e git Not specified
CNA Linux Linux affected e73c838c80dccb9e4f19becc11d9f3cb4a27d483 git Not specified
CNA Linux Linux affected a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31 git Not specified
CNA Linux Linux affected 5.10.241 5.10.261 semver Not specified
CNA Linux Linux affected 5.15.190 5.15.212 semver Not specified
CNA Linux Linux affected 6.1.135 6.1.178 semver Not specified
CNA Linux Linux affected 6.6.88 6.6.145 semver Not specified
CNA Linux Linux affected 6.12.24 6.12.97 semver Not specified
CNA Linux Linux affected 5.4.297 5.5 semver Not specified
CNA Linux Linux affected 6.13.12 6.14 semver Not specified
CNA Linux Linux affected 6.14.3 6.15 semver Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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