{"id":12311,"date":"2026-09-04T18:54:16","date_gmt":"2026-09-04T10:54:16","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-80630"},"modified":"2026-09-04T18:54:16","modified_gmt":"2026-09-04T10:54:16","slug":"cve-2026-80630","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-80630","title":{"rendered":"CVE-2026-80630 [CRITICAL] &#8211; In the Linux kernel, the following vulnerability has been resolved:\n\nnet\/sched: sch_fq_cod"},"content":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>net\/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen<\/p>\n<p>Whenever fq_codel drops packets during peek, it calls<br \/>\nqdisc_tree_reduce_backlog. An issue arises because it calls<br \/>\nqdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops<br \/>\nto zero, but peek returns an skb, the parent&#8217;s qlen_notify callback will be<br \/>\nexecuted even though fq_codel still has 1 packet on the queue and, thus,<br \/>\nwill mistakenly deactivate the parent&#8217;s class causing issues like a recent<br \/>\nreport [1] and a wild memory access in qfq:<\/p>\n<p>[   29.371146][  T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI<br \/>\n[   29.371666][  T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]<br \/>\n[   29.371987][  T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full)<br \/>\n[   29.372384][  T360] Hardware name: Bochs Bochs, BIOS Bochs 01\/01\/2011<br \/>\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<br \/>\n[   29.373544][  T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216<br \/>\n[   29.373800][  T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000<br \/>\n[   29.374079][  T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000<br \/>\n[   29.374368][  T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024<br \/>\n[   29.374649][  T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000<br \/>\n[   29.374926][  T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578<br \/>\n[   29.375207][  T360] FS:  00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000<br \/>\n[   29.375545][  T360] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br \/>\n[   29.375823][  T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0<br \/>\n[   29.376103][  T360] PKRU: 55555554<br \/>\n[   29.376258][  T360] Call Trace:<br \/>\n[   29.376401][  T360]<br \/>\n&#8230;<br \/>\n[   29.376885][  T360] qfq_reset_qdisc (net\/sched\/sch_qfq.c:357 net\/sched\/sch_qfq.c:1487) sch_qfq<br \/>\n[   29.377074][  T360]  qdisc_reset (net\/sched\/sch_generic.c:1057)<br \/>\n[   29.377414][  T360]  __qdisc_destroy (net\/sched\/sch_generic.c:1096)<br \/>\n[   29.377600][  T360]  qdisc_graft (net\/sched\/sch_api.c:1062 net\/sched\/sch_api.c:1053 net\/sched\/sch_api.c:1159)<br \/>\n[   29.378593][  T360]  tc_get_qdisc (net\/sched\/sch_api.c:1528 net\/sched\/sch_api.c:1556)<\/p>\n<p>Fix this by only calling qdisc_tree_reduce_backlog in peek after the<br \/>\nqlen is restored.<\/p>\n<p>[1] http:\/\/lore.kernel.org\/netdev\/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com\/<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>net\/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen<\/p>\n<p>Whenever fq_codel drops packets d<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-12311","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/12311","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12311"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12311"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12311"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}