net_sched: sch_sfq: don't allow 1 packet limit

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Summary

CVECVE-2024-57996
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-02-27 02:15:13 UTC
Updated2026-05-12 13:16:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net_sched: sch_sfq: don't allow 1 packet limit The current implementation does not work correctly with a limit of 1. iproute2 actually checks for this and this patch adds the check in kernel as well. This fixes the following syzkaller reported crash: UBSAN: array-index-out-of-bounds in net/sched/sch_sfq.c:210:6 index 65535 is out of range for type 'struct sfq_head[128]' CPU: 0 PID: 2569 Comm: syz-executor101 Not tainted 5.10.0-smp-DEV #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x125/0x19f lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:148 [inline] __ubsan_handle_out_of_bounds+0xed/0x120 lib/ubsan.c:347 sfq_link net/sched/sch_sfq.c:210 [inline] sfq_dec+0x528/0x600 net/sched/sch_sfq.c:238 sfq_dequeue+0x39b/0x9d0 net/sched/sch_sfq.c:500 sfq_reset+0x13/0x50 net/sched/sch_sfq.c:525 qdisc_reset+0xfe/0x510 net/sched/sch_generic.c:1026 tbf_reset+0x3d/0x100 net/sched/sch_tbf.c:319 qdisc_reset+0xfe/0x510 net/sched/sch_generic.c:1026 dev_reset_queue+0x8c/0x140 net/sched/sch_generic.c:1296 netdev_for_each_tx_queue include/linux/netdevice.h:2350 [inline] dev_deactivate_many+0x6dc/0xc20 net/sched/sch_generic.c:1362 __dev_close_many+0x214/0x350 net/core/dev.c:1468 dev_close_many+0x207/0x510 net/core/dev.c:1506 unregister_netdevice_many+0x40f/0x16b0 net/core/dev.c:10738 unregister_netdevice_queue+0x2be/0x310 net/core/dev.c:10695 unregister_netdevice include/linux/netdevice.h:2893 [inline] __tun_detach+0x6b6/0x1600 drivers/net/tun.c:689 tun_detach drivers/net/tun.c:705 [inline] tun_chr_close+0x104/0x1b0 drivers/net/tun.c:3640 __fput+0x203/0x840 fs/file_table.c:280 task_work_run+0x129/0x1b0 kernel/task_work.c:185 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x5ce/0x2200 kernel/exit.c:931 do_group_exit+0x144/0x310 kernel/exit.c:1046 __do_sys_exit_group kernel/exit.c:1057 [inline] __se_sys_exit_group kernel/exit.c:1055 [inline] __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1055 do_syscall_64+0x6c/0xd0 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fe5e7b52479 Code: Unable to access opcode bytes at RIP 0x7fe5e7b5244f. RSP: 002b:00007ffd3c800398 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe5e7b52479 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 RBP: 00007fe5e7bcd2d0 R08: ffffffffffffffb8 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe5e7bcd2d0 R13: 0000000000000000 R14: 00007fe5e7bcdd20 R15: 00007fe5e7b24270 The crash can be also be reproduced with the following (with a tc recompiled to allow for sfq limits of 1): tc qdisc add dev dummy0 handle 1: root tbf rate 1Kbit burst 100b lat 1s ../iproute2-6.9.0/tc/tc qdisc add dev dummy0 handle 2: parent 1:10 sfq limit 1 ifconfig dummy0 up ping -I dummy0 -f -c2 -W0.1 8.8.8.8 sleep 1 Scenario that triggers the crash: * the first packet is sent and queued in TBF and SFQ; qdisc qlen is 1 * TBF dequeues: it peeks from SFQ which moves the packet to the gso_skb list and keeps qdisc qlen set to 1. TBF is out of tokens so it schedules itself for later. * the second packet is sent and TBF tries to queues it to SFQ. qdisc qlen is now 2 and because the SFQ limit is 1 the packet is dropped by SFQ. At this point qlen is 1, and all of the SFQ slots are empty, however q->tail is not NULL. At this point, assuming no more packets are queued, when sch_dequeue runs again it will decrement the qlen for the current empty slot causing an underflow and the subsequent out of bounds access.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

Problem Types: CWE-129

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e12f6013d0a69660e8b99bfe381b9546ae667328 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 1e6d9d87626cf89eeffb4d943db12cb5b10bf961 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 1b562b7f9231432da40d12e19786c1bd7df653a7 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 35d0137305ae2f97260a9047f445bd4434bd6cc7 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 833e9a1c27b82024db7ff5038a51651f48f05e5e git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 7d8947f2153ee9c5ab4cb17861a11cc45f30e8c4 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 7fefc294204f10a3405f175f4ac2be16d63f135e git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 10685681bafce6febb39770f3387621bf5d67d0b git Not specified
CNA Linux Linux affected 2.6.12 Not specified
CNA Linux Linux unaffected 2.6.12 semver Not specified
CNA Linux Linux unaffected 5.4.297 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.239 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.186 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.129 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.76 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.13 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.2 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/35d0137305ae2f97260a9047f445bd4434bd6cc7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1e6d9d87626cf89eeffb4d943db12cb5b10bf961 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/e12f6013d0a69660e8b99bfe381b9546ae667328 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/833e9a1c27b82024db7ff5038a51651f48f05e5e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/10685681bafce6febb39770f3387621bf5d67d0b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1b562b7f9231432da40d12e19786c1bd7df653a7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7fefc294204f10a3405f175f4ac2be16d63f135e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/03/msg00028.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
lists.debian.org/debian-lts-announce/2025/10/msg00007.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/7d8947f2153ee9c5ab4cb17861a11cc45f30e8c4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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