Linux i915 GPU kernel driver (GEM tiling): MULTI-TENANT ISOLATION: A double-free reachable by racing

Impact

MULTI-TENANT ISOLATION: A double-free reachable by racing I915_GEM_SET_TILING from multiple threads. Double-free in the kernel slab allocator is the most directly weaponisable class here - it gives an attacker with GPU access a well-understood route to arbitrary kernel write and therefore to the host and every co-tenant on the node.

Who can reach it

Any local user or container with a DRM render node - i.e. any tenant that was scheduled a GPU. No privileged capability needed.

What to do

Fix ships in the Linux kernel. Update the kernel and reboot the node - in practice this is a drain plus reboot because the accelerator driver cannot be unloaded while jobs hold device file descriptors. No BIOS or firmware update needed.

References