{"id":"CVE-2026-74267","summary":"net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever codel drops packets during peek, it calls\nqdisc_tree_reduce_backlog. An issue arises because it calls\nqdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops\nto zero, but peek returns an skb, the parent's qlen_notify callback will\nbe executed even though codel still has 1 packet on the queue and, thus,\nwill mistakenly deactivate the parent's class causing issues like a wild\nmemory access when qfq has codel as a child:\n\n[   36.339843][  T370] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n[   36.340408][  T370] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]\n[   36.340737][  T370] CPU: 2 UID: 0 PID: 370 Comm: tc Not tainted 7.1.0-rc5-00287-g66e13b626592 #87 PREEMPT(full)\n[   36.341113][  T370] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[   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\n[   36.342221][  T370] RSP: 0018:ffff8881100ef370 EFLAGS: 00010216\n[   36.342422][  T370] RAX: 0000000000000000 RBX: ffff8881058a9568 RCX: dffffc0000000000\n[   36.342664][  T370] RDX: 1ffff11021064dc3 RSI: ffff888108326e00 RDI: dffffc0000000000\n[   36.342905][  T370] RBP: ffff8881058a8280 R08: dead000000000122 R09: 1bd5a00000000024\n[   36.343140][  T370] R10: fffffbfff2940329 R11: fffffbfff2940329 R12: 0000000000000000\n[   36.343383][  T370] R13: dead000000000100 R14: ffff8881058a9580 R15: ffff8881058a9578\n[   36.343631][  T370] FS:  00007fc04b0ca780(0000) GS:ffff888184fef000(0000) knlGS:0000000000000000\n[   36.343911][  T370] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[   36.344116][  T370] CR2: 0000557c02c02000 CR3: 000000010e0ba000 CR4: 0000000000750ef0\n[   36.344359][  T370] PKRU: 55555554\n[   36.344481][  T370] Call Trace:\n...\n[   36.345054][  T370] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq\n[   36.345222][  T370]  qdisc_reset (net/sched/sch_generic.c:1057)\n[   36.345503][  T370]  __qdisc_destroy (net/sched/sch_generic.c:1096)\n[   36.345677][  T370]  qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[   36.346335][  T370]  tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556)\n\nFix this by only calling qdisc_tree_reduce_backlog in peek after the\nqlen is restored.","modified":"2026-10-20T17:27:13.352378422Z","published":"2026-08-15T05:57:42.263Z","related":["SUSE-SU-2026:24179-1","SUSE-SU-2026:24181-1","SUSE-SU-2026:24182-1","SUSE-SU-2026:24184-1","SUSE-SU-2026:4640-1","SUSE-SU-2026:4660-1","SUSE-SU-2026:4665-1","SUSE-SU-2026:4666-1","SUSE-SU-2026:4667-1","SUSE-SU-2026:4668-1","SUSE-SU-2026:4687-1","SUSE-SU-2026:4706-1","openSUSE-SU-2026:22091-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74267.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/755108bb7a5083e911294c416cfea605dc75632f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7a05af7f58566682b73578b72ca8e53a268c43bd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91e0a793a72374c20ab31a40ccec21373e82e973"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb9cfd874ee884117b33e92a002b9a45b48202f4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e4615aa6bb7802944ae790cb4b3ef8c1b7491af3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e8c6dbadf139cb14ea6ed14add6ed6e88504dedd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/eba49fd85995a3851c597fa2d214f8d21736e1d8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74267.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74267"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cc71a757da78dd4aa1b4a9b19cb011833730ccf2"},{"fixed":"bb9cfd874ee884117b33e92a002b9a45b48202f4"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450"},{"fixed":"7a05af7f58566682b73578b72ca8e53a268c43bd"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"829c49b6b2ff45b043739168fd1245e4e1a91a30"},{"fixed":"eba49fd85995a3851c597fa2d214f8d21736e1d8"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2f9761a94bae33d26e6a81b31b36e7d776d93dc1"},{"fixed":"e8c6dbadf139cb14ea6ed14add6ed6e88504dedd"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4d55144b12e742404bb3f8fee6038bafbf45619d"},{"fixed":"e4615aa6bb7802944ae790cb4b3ef8c1b7491af3"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"342debc12183b51773b3345ba267e9263bdfaaef"},{"fixed":"755108bb7a5083e911294c416cfea605dc75632f"},{"fixed":"91e0a793a72374c20ab31a40ccec21373e82e973"},{"fixed":"52f1da34c9f4d5bdc1e8b44242da5c7ba8db85f3"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.10.241"},{"fixed":"5.10.261"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.15.190"},{"fixed":"5.15.212"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.135"},{"fixed":"6.1.178"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.6.88"},{"fixed":"6.6.145"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.24"},{"fixed":"6.12.97"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.4.297"},{"fixed":"5.5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.13.12"},{"fixed":"6.14"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.14.3"},{"fixed":"6.15"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7a742a9506849d1c1aa71e36c89855ceddc7d58e"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e73c838c80dccb9e4f19becc11d9f3cb4a27d483"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31"}]}],"versions":["v5.10.260","v5.10.259","v5.10.258","v5.10.257","v5.10.256","v5.10.255","v5.10.254","v5.10.253","v5.10.252","v5.10.251","v5.10.250","v5.10.249","v5.10.248","v5.10.247","v5.10.246","v5.10.245","v5.10.244","v5.10.243","v5.10.242","v5.10.241","v5.15.211","v5.15.210","v5.15.209","v5.15.208","v5.15.207","v5.15.206","v5.15.205","v5.15.204","v5.15.203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