CVE-2026-53374

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

drm/amdgpu: zero-initialize GART table on allocation

GART TLB is flushed after unmapping but not after mapping. Since amdgpubocreate_kernel() does not zero-initialize the buffer, when a single PTE is written the TLB may speculatively load other uninitialized entries from the same cacheline. Those garbage entries can appear valid, and a subsequent write to another PTE in the same cacheline may cause the GPU to use a stale garbage PTE from the TLB.

Fix this by calling memsetio() to zero-initialize the GART table with gartpte_flags immediately after allocation.

Using AMDGPUGEMCREATEVRAMCLEARED, SDMA-based clear will not work since SDMA needs GART to be initialized to work.

(cherry picked from commit d9af8263b82b6eaa60c5718e0c6631c5037e4b24)