CVE-2025-68757
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2026-01-05

Last updated on: 2026-01-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: drm/vgem-fence: Fix potential deadlock on release A timer that expires a vgem fence automatically in 10 seconds is now released with timer_delete_sync() from fence->ops.release() called on last dma_fence_put(). In some scenarios, it can run in IRQ context, which is not safe unless TIMER_IRQSAFE is used. One potentially risky scenario was demonstrated in Intel DRM CI trybot, BAT run on machine bat-adlp-6, while working on new IGT subtests syncobj_timeline@stress-* as user space replacements of some problematic test cases of a dma-fence-chain selftest [1]. [117.004338] ================================ [117.004340] WARNING: inconsistent lock state [117.004342] 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 Tainted: G S U [117.004346] -------------------------------- [117.004347] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. [117.004349] swapper/0/0 [HC1[1]:SC1[1]:HE0:SE0] takes: [117.004352] ffff888138f86aa8 ((&fence->timer)){?.-.}-{0:0}, at: __timer_delete_sync+0x4b/0x190 [117.004361] {HARDIRQ-ON-W} state was registered at: [117.004363] lock_acquire+0xc4/0x2e0 [117.004366] call_timer_fn+0x80/0x2a0 [117.004368] __run_timers+0x231/0x310 [117.004370] run_timer_softirq+0x76/0xe0 [117.004372] handle_softirqs+0xd4/0x4d0 [117.004375] __irq_exit_rcu+0x13f/0x160 [117.004377] irq_exit_rcu+0xe/0x20 [117.004379] sysvec_apic_timer_interrupt+0xa0/0xc0 [117.004382] asm_sysvec_apic_timer_interrupt+0x1b/0x20 [117.004385] cpuidle_enter_state+0x12b/0x8a0 [117.004388] cpuidle_enter+0x2e/0x50 [117.004393] call_cpuidle+0x22/0x60 [117.004395] do_idle+0x1fd/0x260 [117.004398] cpu_startup_entry+0x29/0x30 [117.004401] start_secondary+0x12d/0x160 [117.004404] common_startup_64+0x13e/0x141 [117.004407] irq event stamp: 2282669 [117.004409] hardirqs last enabled at (2282668): [<ffffffff8289db71>] _raw_spin_unlock_irqrestore+0x51/0x80 [117.004414] hardirqs last disabled at (2282669): [<ffffffff82882021>] sysvec_irq_work+0x11/0xc0 [117.004419] softirqs last enabled at (2254702): [<ffffffff8289fd00>] __do_softirq+0x10/0x18 [117.004423] softirqs last disabled at (2254725): [<ffffffff813d4ddf>] __irq_exit_rcu+0x13f/0x160 [117.004426] other info that might help us debug this: [117.004429] Possible unsafe locking scenario: [117.004432] CPU0 [117.004433] ---- [117.004434] lock((&fence->timer)); [117.004436] <Interrupt> [117.004438] lock((&fence->timer)); [117.004440] *** DEADLOCK *** [117.004443] 1 lock held by swapper/0/0: [117.004445] #0: ffffc90000003d50 ((&fence->timer)){?.-.}-{0:0}, at: call_timer_fn+0x7a/0x2a0 [117.004450] stack backtrace: [117.004453] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G S U 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 PREEMPT(voluntary) [117.004455] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER [117.004455] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023 [117.004456] Call Trace: [117.004456] <IRQ> [117.004457] dump_stack_lvl+0x91/0xf0 [117.004460] dump_stack+0x10/0x20 [117.004461] print_usage_bug.part.0+0x260/0x360 [117.004463] mark_lock+0x76e/0x9c0 [117.004465] ? register_lock_class+0x48/0x4a0 [117.004467] __lock_acquire+0xbc3/0x2860 [117.004469] lock_acquire+0xc4/0x2e0 [117.004470] ? __timer_delete_sync+0x4b/0x190 [117.004472] ? __timer_delete_sync+0x4b/0x190 [117.004473] __timer_delete_sync+0x68/0x190 [117.004474] ? __timer_delete_sync+0x4b/0x190 [117.004475] timer_delete_sync+0x10/0x20 [117.004476] vgem_fence_release+0x19/0x30 [vgem] [117.004478] dma_fence_release+0xc1/0x3b0 [117.004480] ? dma_fence_release+0xa1/0x3b0 [117.004481] dma_fence_chain_release+0xe7/0x130 [117.004483] dma_fence_release+0xc1/0x3b0 [117.004484] ? _raw_spin_unlock_irqrestore+0x27/0x80 [117.004485] dma_fence_chain_irq_work+0x59/0x80 [117.004487] irq_work_single+0x75/0xa0 [117.004490] irq_work_r ---truncated---
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Meta Information
Published
2026-01-05
Last Modified
2026-01-19
Generated
2026-05-07
AI Q&A
2026-01-05
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
intel linux_kernel 6.17.0-rc7-ci_drm_17270-g7644974e648c
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a potential deadlock issue in the Linux kernel's drm/vgem-fence component. It involves a timer that expires a vgem fence automatically after 10 seconds. The timer is released using timer_delete_sync() from fence->ops.release() when the last dma_fence_put() is called. However, in some scenarios, this release can run in IRQ context, which is unsafe unless TIMER_IRQSAFE is used. This unsafe locking scenario can lead to a deadlock, as demonstrated in testing on Intel hardware with specific DRM tests.


How can this vulnerability impact me? :

This vulnerability can cause a deadlock in the Linux kernel when the drm/vgem-fence timer is released in an unsafe IRQ context. A deadlock can halt or severely disrupt system operations, potentially causing system instability or crashes, especially in environments using the affected DRM components and related fence synchronization mechanisms.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for warnings related to inconsistent lock states and potential deadlocks involving vgem fence timers. Specifically, look for messages similar to 'WARNING: inconsistent lock state' and 'DEADLOCK' in dmesg or /var/log/kern.log. You can use commands like 'dmesg | grep -i vgem' or 'journalctl -k | grep -i fence' to find relevant log entries indicating the issue.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating the Linux kernel to a version where the vulnerability is fixed, as the issue is resolved by properly releasing the vgem fence timer with timer_delete_sync() in fence->ops.release(). Until the update is applied, avoid running workloads or tests that trigger the problematic dma-fence-chain scenarios, such as the IGT subtests syncobj_timeline@stress-*, to reduce the risk of deadlocks.


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