CVE-2025-40288drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices

Description

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices Previously, APU platforms (and other scenarios with uninitialized VRAM managers) triggered a NULL pointer dereference in `ttm_resource_manager_usage()`. The root cause is not that the `struct ttm_resource_manager *man` pointer itself is NULL, but that `man->bdev` (the backing device pointer within the manager) remains uninitialized (NULL) on APUs—since APUs lack dedicated VRAM and do not fully set up VRAM manager structures. When `ttm_resource_manager_usage()` attempts to acquire `man->bdev->lru_lock`, it dereferences the NULL `man->bdev`, leading to a kernel OOPS. 1. **amdgpu_cs.c**: Extend the existing bandwidth control check in `amdgpu_cs_get_threshold_for_moves()` to include a check for `ttm_resource_manager_used()`. If the manager is not used (uninitialized `bdev`), return 0 for migration thresholds immediately—skipping VRAM-specific logic that would trigger the NULL dereference. 2. **amdgpu_kms.c**: Update the `AMDGPU_INFO_VRAM_USAGE` ioctl and memory info reporting to use a conditional: if the manager is used, return the real VRAM usage; otherwise, return 0. This avoids accessing `man->bdev` when it is NULL. 3. **amdgpu_virt.c**: Modify the vf2pf (virtual function to physical function) data write path. Use `ttm_resource_manager_used()` to check validity: if the manager is usable, calculate `fb_usage` from VRAM usage; otherwise, set `fb_usage` to 0 (APUs have no discrete framebuffer to report). This approach is more robust than APU-specific checks because it: - Works for all scenarios where the VRAM manager is uninitialized (not just APUs), - Aligns with TTM's design by using its native helper function, - Preserves correct behavior for discrete GPUs (which have fully initialized `man->bdev` and pass the `ttm_resource_manager_used()` check). v4: use ttm_resource_manager_used(&adev->mman.vram_mgr.manager) instead of checking the adev->gmc.is_app_apu flag (Christian)

Timeline

Scores

No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Deferred.

EPSS (exploitation in 30 days)

0.20% · top 90% of all CVEs (14 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.

Affected products

• Linux · Linux

  • affected d38ceaf99ed015f2a0b9af3499791bd3a3daae21 – < e70113b741ba253886cd71dbadfe3ea444bb2f5c
  • affected d38ceaf99ed015f2a0b9af3499791bd3a3daae21 – < 1243e396148a65bb6c42a2b70fe43e50c16c494f
  • affected d38ceaf99ed015f2a0b9af3499791bd3a3daae21 – < 43aa61c18a3a45042b098b7a1186ffb29364002c
  • affected d38ceaf99ed015f2a0b9af3499791bd3a3daae21 – < 070bdce18fb12a49eb9c421e57df17d2ad29bf5f
  • affected d38ceaf99ed015f2a0b9af3499791bd3a3daae21 – < 883f309add55060233bf11c1ea6947140372920f

• Linux · Linux

  • affected 4.2
  • unaffected < 4.2
  • unaffected 6.1.159 – ≤ 6.1.*
  • unaffected 6.6.117 – ≤ 6.6.*
  • unaffected 6.12.59 – ≤ 6.12.*
  • unaffected 6.17.9 – ≤ 6.17.*
  • unaffected 6.18 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2025-201567 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

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Record last updated 11 May 2026, 21:46 UTC.