PatchSiren cyber security CVE debrief

CVE-2026-46276 Linux CVE debrief

A vulnerability was discovered in the Linux kernel related to the initialization of zero-size GDS range on RDNA4 hardware. The RDNA4 (GFX 12) hardware removes the GDS, GWS, and OA on-chip memory resources. However, the gfx_v12_0 initialization code correctly sets the sizes of these resources to zero to reflect this. The issue arises when amdgpu_ttm_init() unconditionally calls amdgpu_ttm_init_on_chip() for each of these resources, regardless of their size. When the size is zero, amdgpu_ttm_init_on_chip() calls ttm_range_man_init(), which in turn calls drm_mm_init(mm, 0, 0). This leads to a crash during the modprobe of amdgpu on an RX 9070 XT due to a DRM_MM_BUG_ON() assertion. To fix this, a check was added to return 0 early from amdgpu_ttm_init_on_chip() when the size is zero, preventing the registration of TTM resource managers for absent hardware resources.