CVE-2026-68272drm/amdgpu: validate CP_GFX_SHADOW chunk size in CS pass1

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: validate CP_GFX_SHADOW chunk size in CS pass1 Add a minimum-length check for the AMDGPU_CHUNK_ID_CP_GFX_SHADOW chunk in amdgpu_cs_pass1(), matching the gate already present for the IB, FENCE and BO_HANDLES chunk types. The CP_GFX_SHADOW case previously shared a bare break with the dependency and syncobj chunk types, which do not dereference a fixed-size struct. When userspace submits this chunk with length_dw == 0, vmemdup_array_user() is called with size 0 and returns ZERO_SIZE_PTR, which passes the IS_ERR() check. amdgpu_cs_p2_shadow() then dereferences chunk->kdata as a struct drm_amdgpu_cs_chunk_cp_gfx_shadow (reading shadow->flags), faulting on the ZERO_SIZE_PTR and causing a NULL-pointer dereference. This is reachable by an unprivileged process in the render group. Reject undersized chunks with -EINVAL during pass1 so the bad submission is rejected before pass2 ever dereferences the data. (cherry picked from commit 7f61b2eef7415eccdb40850aca0de94211948657)

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3f190956404da55560056ce20606010e18bc059c
• https://git.kernel.org/stable/c/2aa9ea2bd5146d237c8cc16d8737d878b0298a94
• https://git.kernel.org/stable/c/315d2e5741a81b0be763e80413a2677e22b7e596
• https://git.kernel.org/stable/c/24668ca3ec19434d7a9574bf9112f2b0614c3a4e
• https://git.kernel.org/stable/c/84c4c36acd5c4b2558b5069f869a165b2c655c84