CVE-2026-68276

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

drm/amdgpu/gfx: fix cleaner shader IB buffer overflow

The cleaner shader sysfs path allocates a 16-dword (64 byte) IB but incorrectly fills (alignmask + 1) dwords. On GFX rings alignmask is 0xff, so the loop wrote 256 dwords into a 64-byte buffer, causing a kernel page fault.

The IB only needs to be a minimal NOP shell to schedule the job; the cleaner shader itself is emitted on the ring via emitcleanershader(). Fill 16 dwords to match the allocation.

v2: Use ibsizedw variable (Lijo)

(cherry picked from commit bf21af331ebf72d0935fd70c73192414a422c03a)