CVE-2026-99150

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

drm/amdgpu: don't drop the runtime PM reference twice in amdgpu gpr

amdgpu debugfs gpr read() drops its runtime PM reference right after reading the wave registers. When copying them to userspace fails, it jumps to the err label, which drops the reference a second time. A read into a bad buffer on Navi31 either steals a reference somebody else holds (power/runtime usage goes from 1 to 0) or underflows the count:

amdgpu 0000:03:00.0: Runtime PM usage count underflow!

The registers are already in the kernel buffer at that point, so finish the hardware access first and copy the buffer with a single copy to user() instead of the put user() loop with its own error path.

(cherry picked from commit 31035bbd74f7c3e10c163db875b8e67f8b50ee6a)