Linux Kernel up to 6.12.62/6.17.12/6.18.1 vgem-fence timer_delete_sync deadlock

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.12.62/6.17.12/6.18.1. This affects the function timer_delete_sync of the component vgem-fence. This manipulation causes deadlock. This vulnerability appears as CVE-2025-68757. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.62/6.17.12/6.18.1. It has been declared as critical. Affected by this vulnerability is the function timer_delete_sync of the component vgem-fence. The manipulation with an unknown input leads to a deadlock vulnerability. The CWE definition for the vulnerability is CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. As an impact it is known to affect availability. The summary by CVE is:

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---

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-68757 since 12/24/2025. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 281766 (Linux Distros Unpatched Vulnerability : CVE-2025-68757), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.63, 6.17.13, 6.18.2 or 6.19-rc1 eliminates this vulnerability. Applying the patch 338e388c0d80ffc04963b6b0ec702ffdfd2c4eba/4f335cb8fad69b2be5accf0ebac3a8b345915f4e/1f0ca9d3e7c38a39f1f12377c24decf0bba46e54/78b4d6463e9e69e5103f98b367f8984ad12cdc6f is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (281766), EUVD (EUVD-2026-0884) and CERT Bund (WID-SEC-2026-0009). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Microsoft Azure Linux
• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.12.55
• 6.12.56
• 6.12.57
• 6.12.58
• 6.12.59
• 6.12.60
• 6.12.61
• 6.12.62
• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3
• 6.17.4
• 6.17.5
• 6.17.6
• 6.17.7
• 6.17.8
• 6.17.9
• 6.17.10
• 6.17.11
• 6.17.12
• 6.18.0
• 6.18.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

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Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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