{"cve":"CVE-2026-80630","nvd":{"published":"2026-08-28T08:16:47.850","modified":"2026-10-16T20:18:04.520","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever fq_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 be\nexecuted even though fq_codel still has 1 packet on the queue and, thus,\nwill mistakenly deactivate the parent's class causing issues like a recent\nreport [1] and a wild memory access in qfq:\n\n[   29.371146][  T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n[   29.371666][  T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]\n[   29.371987][  T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full)\n[   29.372384][  T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[   29.372620][  T360] 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[   29.373544][  T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216\n[   29.373800][  T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000\n[   29.374079][  T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000\n[   29.374368][  T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024\n[   29.374649][  T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000\n[   29.374926][  T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578\n[   29.375207][  T360] FS:  00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000\n[   29.375545][  T360] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[   29.375823][  T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0\n[   29.376103][  T360] PKRU: 55555554\n[   29.376258][  T360] Call Trace:\n[   29.376401][  T360]  <TASK>\n...\n[   29.376885][  T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq\n[   29.377074][  T360]  qdisc_reset (net/sched/sch_generic.c:1057)\n[   29.377414][  T360]  __qdisc_destroy (net/sched/sch_generic.c:1096)\n[   29.377600][  T360]  qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[   29.378593][  T360]  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.\n\n[1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":[],"references":["https://git.kernel.org/stable/c/0500af8630c3253f0dde879bd3a73a06bb2f2b3f","https://git.kernel.org/stable/c/097f6fc7b1ae362dd7a9444b2572162fda73b284","https://git.kernel.org/stable/c/20dd591d8f951e1e6aca5052be8785e6181055e2","https://git.kernel.org/stable/c/3e515188393e62a718ccebee651ee74514104ff6","https://git.kernel.org/stable/c/7c09843fd2b44d9bf0de798683861d1aecd62a08"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-80630","score":0.00755,"percentile":0.54835,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}