CVE-2025-38354

Published Jul 25, 2025

Last updated 10 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: drm/msm/gpu: Fix crash when throttling GPU immediately during boot There is a small chance that the GPU is already hot during boot. In that case, the call to of_devfreq_cooling_register() will immediately try to apply devfreq cooling, as seen in the following crash: Unable to handle kernel paging request at virtual address 0000000000014110 pc : a6xx_gpu_busy+0x1c/0x58 [msm] lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm] Call trace: a6xx_gpu_busy+0x1c/0x58 [msm] (P) devfreq_simple_ondemand_func+0x3c/0x150 devfreq_update_target+0x44/0xd8 qos_max_notifier_call+0x30/0x84 blocking_notifier_call_chain+0x6c/0xa0 pm_qos_update_target+0xd0/0x110 freq_qos_apply+0x3c/0x74 apply_constraint+0x88/0x148 __dev_pm_qos_update_request+0x7c/0xcc dev_pm_qos_update_request+0x38/0x5c devfreq_cooling_set_cur_state+0x98/0xf0 __thermal_cdev_update+0x64/0xb4 thermal_cdev_update+0x4c/0x58 step_wise_manage+0x1f0/0x318 __thermal_zone_device_update+0x278/0x424 __thermal_cooling_device_register+0x2bc/0x308 thermal_of_cooling_device_register+0x10/0x1c of_devfreq_cooling_register_power+0x240/0x2bc of_devfreq_cooling_register+0x14/0x20 msm_devfreq_init+0xc4/0x1a0 [msm] msm_gpu_init+0x304/0x574 [msm] adreno_gpu_init+0x1c4/0x2e0 [msm] a6xx_gpu_init+0x5c8/0x9c8 [msm] adreno_bind+0x2a8/0x33c [msm] ... At this point we haven't initialized the GMU at all yet, so we cannot read the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag accordingly. This means the df->suspended flag does not match the actual devfreq state after initialization and msm_devfreq_get_dev_status() will end up accessing GMU registers, causing the crash. Fix this by setting df->suspended correctly during initialization. Patchwork: https://patchwork.freedesktop.org/patch/650772/
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

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