5.5 - CVE-2024-50144

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

drm/xe: fix unbalanced rpm put() with fence_fini()

Currently we can call fence_fini() twice if something goes wrong when sending the GuC CT for the tlb request, since we signal the fence and return an error, leading to the caller also calling fini() on the error path in the case of stack version of the flow, which leads to an extra rpm put() which might later cause device to enter suspend when it shouldn't. It looks like we can just drop the fini() call since the fence signaller side will already call this for us.

There are known mysterious splats with device going to sleep even with an rpm ref, and this could be one candidate.

v2 (Matt B):
- Prefer warning if we detect double fini()

(cherry picked from commit cfcbc0520d5055825f0647ab922b655688605183)