CVE-2022-49691

Published Feb 26, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: erspan: do not assume transport header is always set Rewrite tests in ip6erspan_tunnel_xmit() and erspan_fb_xmit() to not assume transport header is set. syzbot reported: WARNING: CPU: 0 PID: 1350 at include/linux/skbuff.h:2911 skb_transport_header include/linux/skbuff.h:2911 [inline] WARNING: CPU: 0 PID: 1350 at include/linux/skbuff.h:2911 ip6erspan_tunnel_xmit+0x15af/0x2eb0 net/ipv6/ip6_gre.c:963 Modules linked in: CPU: 0 PID: 1350 Comm: aoe_tx0 Not tainted 5.19.0-rc2-syzkaller-00160-g274295c6e53f #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:skb_transport_header include/linux/skbuff.h:2911 [inline] RIP: 0010:ip6erspan_tunnel_xmit+0x15af/0x2eb0 net/ipv6/ip6_gre.c:963 Code: 0f 47 f0 40 88 b5 7f fe ff ff e8 8c 16 4b f9 89 de bf ff ff ff ff e8 a0 12 4b f9 66 83 fb ff 0f 85 1d f1 ff ff e8 71 16 4b f9 <0f> 0b e9 43 f0 ff ff e8 65 16 4b f9 48 8d 85 30 ff ff ff ba 60 00 RSP: 0018:ffffc90005daf910 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 000000000000ffff RCX: 0000000000000000 RDX: ffff88801f032100 RSI: ffffffff882e8d3f RDI: 0000000000000003 RBP: ffffc90005dafab8 R08: 0000000000000003 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000000 R12: ffff888024f21d40 R13: 000000000000a288 R14: 00000000000000b0 R15: ffff888025a2e000 FS: 0000000000000000(0000) GS:ffff88802c800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e425000 CR3: 000000006d099000 CR4: 0000000000152ef0 Call Trace: <TASK> __netdev_start_xmit include/linux/netdevice.h:4805 [inline] netdev_start_xmit include/linux/netdevice.h:4819 [inline] xmit_one net/core/dev.c:3588 [inline] dev_hard_start_xmit+0x188/0x880 net/core/dev.c:3604 sch_direct_xmit+0x19f/0xbe0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3815 [inline] __dev_queue_xmit+0x14a1/0x3900 net/core/dev.c:4219 dev_queue_xmit include/linux/netdevice.h:2994 [inline] tx+0x6a/0xc0 drivers/block/aoe/aoenet.c:63 kthread+0x1e7/0x3b0 drivers/block/aoe/aoecmd.c:1229 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 </TASK>
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: cgroup: Avoid iteration of dying tasks with zero refcount The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") extended the lifetime of tasks on the dying_tasks list. The iterators have provision to go through dying_tasks because of dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however, it was expected that such tasks can obtain a new reference (that is possible before cgroup_task_release()/put_task_struct_rcu_user()). The tasks after cgroup_task_release() and before cgroup_task_free() are subject to race when they may or may not have ->usage count > 0. The race window is between css_task_iter_next() invocations when css_set_lock is released and we may arrive at a new ->task_pos. The iterator should not attempt to resurrect tasks whose ->usage count dropped to zero. (When that happens, __put_task_struct_rcu_cb() is already imminent and the returned task_struct would could be used after free.) As for the fix, we cannot simply check the signal->live count of a task on the dying list because that won't distinguish regular zombies waiting to be reaped from RCU remnant tasks that are going to be free'd. Therefore add an extra check to rule out ->usage==0 tasks from any iteration. The repeat: loop in css_task_iter_advance() doesn't consider ->usage count, so add a new loop to css_task_iter_next() to skip de-used tasks on the dying_list. Rough illustration of the possible race R (reader of cgroup.procs) T (thread) L (group leader) --------------------------------- -------------------------------- -------------------------------- L exits, signal->live > 0 cgroup_task_dead(L) css_set_skip_task_iters() // skips only cset->tasks list_add_tail(&L->cg_list, &cset->dying_tasks) css_task_iter_next() take css_set_lock css_task_iter_advance() leader && signal->live != 0 => it->task_pos = &L->cg_list release css_set_lock T exits --signal->live == 0 cgroup_task_dead(T) // css_set_lock release_task(T) cgroup_task_release(T) release_task(L) // zap_leader cgroup_task_release(L) put_task_struct_rcu_user(L) ...RCU... put_task_struct(L) L->usage = 0 /* L still on dying_tasks */ ...RCU... __put_task_struct(L) css_task_iter_next() // another iteration take css_set_lock it->task_pos = &L->cg_list get_task_struct(L) => addition on 0 drop css_set_lock cgroup_task_free(L) css_set_skip_task_iters() // dying skip comes too late free_task(L) cgroup_procs_show() task_pid_vnr(L)•CVE-2026-98163