CVE-2025-37754

Published May 1, 2025

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: drm/i915/huc: Fix fence not released on early probe errors HuC delayed loading fence, introduced with commit 27536e03271da ("drm/i915/huc: track delayed HuC load with a fence"), is registered with object tracker early on driver probe but unregistered only from driver remove, which is not called on early probe errors. Since its memory is allocated under devres, then released anyway, it may happen to be allocated again to the fence and reused on future driver probes, resulting in kernel warnings that taint the kernel: <4> [309.731371] ------------[ cut here ]------------ <3> [309.731373] ODEBUG: init destroyed (active state 0) object: ffff88813d7dd2e0 object type: i915_sw_fence hint: sw_fence_dummy_notify+0x0/0x20 [i915] <4> [309.731575] WARNING: CPU: 2 PID: 3161 at lib/debugobjects.c:612 debug_print_object+0x93/0xf0 ... <4> [309.731693] CPU: 2 UID: 0 PID: 3161 Comm: i915_module_loa Tainted: G U 6.14.0-CI_DRM_16362-gf0fd77956987+ #1 ... <4> [309.731700] RIP: 0010:debug_print_object+0x93/0xf0 ... <4> [309.731728] Call Trace: <4> [309.731730] <TASK> ... <4> [309.731949] __debug_object_init+0x17b/0x1c0 <4> [309.731957] debug_object_init+0x34/0x50 <4> [309.732126] __i915_sw_fence_init+0x34/0x60 [i915] <4> [309.732256] intel_huc_init_early+0x4b/0x1d0 [i915] <4> [309.732468] intel_uc_init_early+0x61/0x680 [i915] <4> [309.732667] intel_gt_common_init_early+0x105/0x130 [i915] <4> [309.732804] intel_root_gt_init_early+0x63/0x80 [i915] <4> [309.732938] i915_driver_probe+0x1fa/0xeb0 [i915] <4> [309.733075] i915_pci_probe+0xe6/0x220 [i915] <4> [309.733198] local_pci_probe+0x44/0xb0 <4> [309.733203] pci_device_probe+0xf4/0x270 <4> [309.733209] really_probe+0xee/0x3c0 <4> [309.733215] __driver_probe_device+0x8c/0x180 <4> [309.733219] driver_probe_device+0x24/0xd0 <4> [309.733223] __driver_attach+0x10f/0x220 <4> [309.733230] bus_for_each_dev+0x7d/0xe0 <4> [309.733236] driver_attach+0x1e/0x30 <4> [309.733239] bus_add_driver+0x151/0x290 <4> [309.733244] driver_register+0x5e/0x130 <4> [309.733247] __pci_register_driver+0x7d/0x90 <4> [309.733251] i915_pci_register_driver+0x23/0x30 [i915] <4> [309.733413] i915_init+0x34/0x120 [i915] <4> [309.733655] do_one_initcall+0x62/0x3f0 <4> [309.733667] do_init_module+0x97/0x2a0 <4> [309.733671] load_module+0x25ff/0x2890 <4> [309.733688] init_module_from_file+0x97/0xe0 <4> [309.733701] idempotent_init_module+0x118/0x330 <4> [309.733711] __x64_sys_finit_module+0x77/0x100 <4> [309.733715] x64_sys_call+0x1f37/0x2650 <4> [309.733719] do_syscall_64+0x91/0x180 <4> [309.733763] entry_SYSCALL_64_after_hwframe+0x76/0x7e <4> [309.733792] </TASK> ... <4> [309.733806] ---[ end trace 0000000000000000 ]--- That scenario is most easily reproducible with igt@i915_module_load@reload-with-fault-injection. Fix the issue by moving the cleanup step to driver release path. (cherry picked from commit 795dbde92fe5c6996a02a5b579481de73035e7bf)
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