CVE-2023-53366

Published Sep 17, 2025

Last updated 9 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: block: be a bit more careful in checking for NULL bdev while polling Wei reports a crash with an application using polled IO: PGD 14265e067 P4D 14265e067 PUD 47ec50067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 21915 Comm: iocore_0 Kdump: loaded Tainted: G S 5.12.0-0_fbk12_clang_7346_g1bb6f2e7058f #1 Hardware name: Wiwynn Delta Lake MP T8/Delta Lake-Class2, BIOS Y3DLM08 04/10/2022 RIP: 0010:bio_poll+0x25/0x200 Code: 0f 1f 44 00 00 0f 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec 28 65 48 8b 04 25 28 00 00 00 48 89 44 24 20 48 8b 47 08 <48> 8b 80 70 02 00 00 4c 8b 70 50 8b 6f 34 31 db 83 fd ff 75 25 65 RSP: 0018:ffffc90005fafdf8 EFLAGS: 00010292 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 74b43cd65dd66600 RDX: 0000000000000003 RSI: ffffc90005fafe78 RDI: ffff8884b614e140 RBP: ffff88849964df78 R08: 0000000000000000 R09: 0000000000000008 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88849964df00 R13: ffffc90005fafe78 R14: ffff888137d3c378 R15: 0000000000000001 FS: 00007fd195000640(0000) GS:ffff88903f400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000270 CR3: 0000000466121001 CR4: 00000000007706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: iocb_bio_iopoll+0x1d/0x30 io_do_iopoll+0xac/0x250 __se_sys_io_uring_enter+0x3c5/0x5a0 ? __x64_sys_write+0x89/0xd0 do_syscall_64+0x2d/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x94f225d Code: 24 cc 00 00 00 41 8b 84 24 d0 00 00 00 c1 e0 04 83 e0 10 41 09 c2 8b 33 8b 53 04 4c 8b 43 18 4c 63 4b 0c b8 aa 01 00 00 0f 05 <85> c0 0f 88 85 00 00 00 29 03 45 84 f6 0f 84 88 00 00 00 41 f6 c7 RSP: 002b:00007fd194ffcd88 EFLAGS: 00000202 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 00007fd194ffcdc0 RCX: 00000000094f225d RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007fd194ffcdb0 R08: 0000000000000000 R09: 0000000000000008 R10: 0000000000000001 R11: 0000000000000202 R12: 00007fd269d68030 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000 which is due to bio->bi_bdev being NULL. This can happen if we have two tasks doing polled IO, and task B ends up completing IO from task A if they are sharing a poll queue. If task B completes the IO and puts the bio into our cache, then it can allocate that bio again before task A is done polling for it. As that would necessitate a preempt between the two tasks, it's enough to just be a bit more careful in checking for whether or not bio->bi_bdev is NULL.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
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
CWE-476
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-476

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