Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

drm/i915/vma: Fix UAF on destroy against retire race

Object debugging tools were sporadically reporting illegal attempts to free a still active i915 VMA object when parking a GT believed to be idle.

[161.359441] ODEBUG: free active (active state 0) object: ffff88811643b958 object type: i915_active hint: __i915_vma_active+0x0/0x50 [i915] [161.360082] WARNING: CPU: 5 PID: 276 at lib/debugobjects.c:514 debug_print_object+0x80/0xb0 ... [161.360304] CPU: 5 PID: 276 Comm: kworker/5:2 Not tainted 6.5.0-rc1-CI_DRM_13375-g003f860e5577+ #1 [161.360314] Hardware name: Intel Corporation Rocket Lake Client Platform/RocketLake S UDIMM 6L RVP, BIOS RKLSFWI1.R00.3173.A03.2204210138 04/21/2022 [161.360322] Workqueue: i915-unordered __intel_wakeref_put_work [i915] [161.360592] RIP: 0010:debug_print_object+0x80/0xb0 ... [161.361347] debug_object_free+0xeb/0x110 [161.361362] i915_active_fini+0x14/0x130 [i915] [161.361866] release_references+0xfe/0x1f0 [i915] [161.362543] i915_vma_parked+0x1db/0x380 [i915] [161.363129] __gt_park+0x121/0x230 [i915] [161.363515] ____intel_wakeref_put_last+0x1f/0x70 [i915]

That has been tracked down to be happening when another thread is deactivating the VMA inside __active_retire() helper, after the VMA's active counter has been already decremented to 0, but before deactivation of the VMA's object is reported to the object debugging tool.

We could prevent from that race by serializing i915_ac…