CVE-2022-49723

Published Feb 26, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: drm/i915/reset: Fix error_state_read ptr + offset use Fix our pointer offset usage in error_state_read when there is no i915_gpu_coredump but buf offset is non-zero. This fixes a kernel page fault can happen when multiple tests are running concurrently in a loop and one is producing engine resets and consuming the i915 error_state dump while the other is forcing full GT resets. (takes a while to trigger). The dmesg call trace: [ 5590.803000] BUG: unable to handle page fault for address: ffffffffa0b0e000 [ 5590.803009] #PF: supervisor read access in kernel mode [ 5590.803013] #PF: error_code(0x0000) - not-present page [ 5590.803016] PGD 5814067 P4D 5814067 PUD 5815063 PMD 109de4067 PTE 0 [ 5590.803022] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 5590.803026] CPU: 5 PID: 13656 Comm: i915_hangman Tainted: G U 5.17.0-rc5-ups69-guc-err-capt-rev6+ #136 [ 5590.803033] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-M LP4x RVP, BIOS ADLPFWI1.R00. 3031.A02.2201171222 01/17/2022 [ 5590.803039] RIP: 0010:memcpy_erms+0x6/0x10 [ 5590.803045] Code: fe ff ff cc eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe [ 5590.803054] RSP: 0018:ffffc90003a8fdf0 EFLAGS: 00010282 [ 5590.803057] RAX: ffff888107ee9000 RBX: ffff888108cb1a00 RCX: 0000000000000f8f [ 5590.803061] RDX: 0000000000001000 RSI: ffffffffa0b0e000 RDI: ffff888107ee9071 [ 5590.803065] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 [ 5590.803069] R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000019 [ 5590.803073] R13: 0000000000174fff R14: 0000000000001000 R15: ffff888107ee9000 [ 5590.803077] FS: 00007f62a99bee80(0000) GS:ffff88849f880000(0000) knlGS:0000000000000000 [ 5590.803082] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5590.803085] CR2: ffffffffa0b0e000 CR3: 000000010a1a8004 CR4: 0000000000770ee0 [ 5590.803089] PKRU: 55555554 [ 5590.803091] Call Trace: [ 5590.803093] <TASK> [ 5590.803096] error_state_read+0xa1/0xd0 [i915] [ 5590.803175] kernfs_fop_read_iter+0xb2/0x1b0 [ 5590.803180] new_sync_read+0x116/0x1a0 [ 5590.803185] vfs_read+0x114/0x1b0 [ 5590.803189] ksys_read+0x63/0xe0 [ 5590.803193] do_syscall_64+0x38/0xc0 [ 5590.803197] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 5590.803201] RIP: 0033:0x7f62aaea5912 [ 5590.803204] Code: c0 e9 b2 fe ff ff 50 48 8d 3d 5a b9 0c 00 e8 05 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 [ 5590.803213] RSP: 002b:00007fff5b659ae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 5590.803218] RAX: ffffffffffffffda RBX: 0000000000100000 RCX: 00007f62aaea5912 [ 5590.803221] RDX: 000000000008b000 RSI: 00007f62a8c4000f RDI: 0000000000000006 [ 5590.803225] RBP: 00007f62a8bcb00f R08: 0000000000200010 R09: 0000000000101000 [ 5590.803229] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000006 [ 5590.803233] R13: 0000000000075000 R14: 00007f62a8acb010 R15: 0000000000200000 [ 5590.803238] </TASK> [ 5590.803240] Modules linked in: i915 ttm drm_buddy drm_dp_helper drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops prime_numbers nfnetlink br_netfilter overlay mei_pxp mei_hdcp x86_pkg_temp_thermal coretemp kvm_intel snd_hda_codec_hdmi snd_hda_intel ---truncated---
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