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CVE-2025-40288 (GCVE-0-2025-40288)

Vulnerability from cvelistv5 – Published: 2025-12-06 21:51 – Updated: 2026-05-11 21:46
VLAI
Title
drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices
Summary
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)
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d38ceaf99ed015f2a0b9af3499791bd3a3daae21 , < e70113b741ba253886cd71dbadfe3ea444bb2f5c (git)
Affected: d38ceaf99ed015f2a0b9af3499791bd3a3daae21 , < 1243e396148a65bb6c42a2b70fe43e50c16c494f (git)
Affected: d38ceaf99ed015f2a0b9af3499791bd3a3daae21 , < 43aa61c18a3a45042b098b7a1186ffb29364002c (git)
Affected: d38ceaf99ed015f2a0b9af3499791bd3a3daae21 , < 070bdce18fb12a49eb9c421e57df17d2ad29bf5f (git)
Affected: d38ceaf99ed015f2a0b9af3499791bd3a3daae21 , < 883f309add55060233bf11c1ea6947140372920f (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.2
Unaffected: 0 , < 4.2 (semver)
Unaffected: 6.1.159 , ≤ 6.1.* (semver)
Unaffected: 6.6.117 , ≤ 6.6.* (semver)
Unaffected: 6.12.59 , ≤ 6.12.* (semver)
Unaffected: 6.17.9 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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When `ttm_resource_manager_usage()` attempts to\\nacquire `man-\u003ebdev-\u003elru_lock`, it dereferences the NULL `man-\u003ebdev`, leading to\\na kernel OOPS.\\n\\n1. **amdgpu_cs.c**: Extend the existing bandwidth control check in\\n   `amdgpu_cs_get_threshold_for_moves()` to include a check for\\n   `ttm_resource_manager_used()`. If the manager is not used (uninitialized\\n   `bdev`), return 0 for migration thresholds immediately\u2014skipping VRAM-specific\\n   logic that would trigger the NULL dereference.\\n\\n2. **amdgpu_kms.c**: Update the `AMDGPU_INFO_VRAM_USAGE` ioctl and memory info\\n   reporting to use a conditional: if the manager is used, return the real VRAM\\n   usage; otherwise, return 0. This avoids accessing `man-\u003ebdev` when it is\\n   NULL.\\n\\n3. **amdgpu_virt.c**: Modify the vf2pf (virtual function to physical function)\\n   data write path. 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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-30T10:34:32+00:00",
      "cve": "CVE-2025-40288",
      "id": "CVE-2025-40288",
      "initial_release_date": "2025-12-06T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40288.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-29T01:14:59Z",
      "cve": "CVE-2025-40288",
      "id": "CVE-2025-40288",
      "initial_release_date": "2025-12-08T00:22:54Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "688",
      "product_status:known_not_affected": "141",
      "product_status:recommended": "384",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-40288",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40288.json",
      "version": "43"
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  }
}



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