CVE-2025-68757 — drm/vgem-fence: Fix potential deadlock on release

Affected: Linux

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+0…

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CVE-2025-68757 — drm/vgem-fence: Fix potential deadlock on release