CVE-2023-53455

Published Oct 1, 2025

Last updated 9 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: drm/vc4: drop all currently held locks if deadlock happens If vc4_hdmi_reset_link() returns -EDEADLK, it means that a deadlock happened in the locking context. This situation should be addressed by dropping all currently held locks and block until the contended lock becomes available. Currently, vc4 is not dealing with the deadlock properly, producing the following output when PROVE_LOCKING is enabled: [ 825.612809] ------------[ cut here ]------------ [ 825.612852] WARNING: CPU: 1 PID: 116 at drivers/gpu/drm/drm_modeset_lock.c:276 drm_modeset_drop_locks+0x60/0x68 [drm] [ 825.613458] Modules linked in: 8021q mrp garp stp llc raspberrypi_cpufreq brcmfmac brcmutil crct10dif_ce hci_uart cfg80211 btqca btbcm bluetooth vc4 raspberrypi_hwmon snd_soc_hdmi_codec cec clk_raspberrypi ecdh_generic drm_display_helper ecc rfkill drm_dma_helper drm_kms_helper pwm_bcm2835 bcm2835_thermal bcm2835_rng rng_core i2c_bcm2835 drm fuse ip_tables x_tables ipv6 [ 825.613735] CPU: 1 PID: 116 Comm: kworker/1:2 Tainted: G W 6.1.0-rc6-01399-g941aae326315 #3 [ 825.613759] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT) [ 825.613777] Workqueue: events output_poll_execute [drm_kms_helper] [ 825.614038] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 825.614063] pc : drm_modeset_drop_locks+0x60/0x68 [drm] [ 825.614603] lr : drm_helper_probe_detect+0x120/0x1b4 [drm_kms_helper] [ 825.614829] sp : ffff800008313bf0 [ 825.614844] x29: ffff800008313bf0 x28: ffffcd7778b8b000 x27: 0000000000000000 [ 825.614883] x26: 0000000000000001 x25: 0000000000000001 x24: ffff677cc35c2758 [ 825.614920] x23: ffffcd7707d01430 x22: ffffcd7707c3edc7 x21: 0000000000000001 [ 825.614958] x20: 0000000000000000 x19: ffff800008313c10 x18: 000000000000b6d3 [ 825.614995] x17: ffffcd777835e214 x16: ffffcd7777cef870 x15: fffff81000000000 [ 825.615033] x14: 0000000000000000 x13: 0000000000000099 x12: 0000000000000002 [ 825.615070] x11: 72917988020af800 x10: 72917988020af800 x9 : 72917988020af800 [ 825.615108] x8 : ffff677cc665e0a8 x7 : d00a8c180000110c x6 : ffffcd77774c0054 [ 825.615145] x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 [ 825.615181] x2 : ffff677cc55e1880 x1 : ffffcd7777cef8ec x0 : ffff800008313c10 [ 825.615219] Call trace: [ 825.615232] drm_modeset_drop_locks+0x60/0x68 [drm] [ 825.615773] drm_helper_probe_detect+0x120/0x1b4 [drm_kms_helper] [ 825.616003] output_poll_execute+0xe4/0x224 [drm_kms_helper] [ 825.616233] process_one_work+0x2b4/0x618 [ 825.616264] worker_thread+0x24c/0x464 [ 825.616288] kthread+0xec/0x110 [ 825.616310] ret_from_fork+0x10/0x20 [ 825.616335] irq event stamp: 7634 [ 825.616349] hardirqs last enabled at (7633): [<ffffcd777831ee90>] _raw_spin_unlock_irq+0x3c/0x78 [ 825.616384] hardirqs last disabled at (7634): [<ffffcd7778315a78>] __schedule+0x134/0x9f0 [ 825.616411] softirqs last enabled at (7630): [<ffffcd7707aacea0>] local_bh_enable+0x4/0x30 [ipv6] [ 825.617019] softirqs last disabled at (7618): [<ffffcd7707aace70>] local_bh_disable+0x4/0x30 [ipv6] [ 825.617586] ---[ end trace 0000000000000000 ]--- Therefore, deal with the deadlock as suggested by [1], using the function drm_modeset_backoff(). [1] https://docs.kernel.org/gpu/drm-kms.html?highlight=kms#kms-locking
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