{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-40288", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.184Z", "datePublished": "2025-12-06T21:51:14.440Z", "dateUpdated": "2025-12-06T21:51:14.440Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-12-06T21:51:14.440Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices\n\nPreviously, APU platforms (and other scenarios with uninitialized VRAM managers)\ntriggered a NULL pointer dereference in `ttm_resource_manager_usage()`. The root\ncause is not that the `struct ttm_resource_manager *man` pointer itself is NULL,\nbut that `man->bdev` (the backing device pointer within the manager) remains\nuninitialized (NULL) on APUs\u2014since APUs lack dedicated VRAM and do not fully\nset up VRAM manager structures. When `ttm_resource_manager_usage()` attempts to\nacquire `man->bdev->lru_lock`, it dereferences the NULL `man->bdev`, 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->bdev` when it is\n NULL.\n\n3. **amdgpu_virt.c**: Modify the vf2pf (virtual function to physical function)\n data write path. Use `ttm_resource_manager_used()` to check validity: if the\n manager is usable, calculate `fb_usage` from VRAM usage; otherwise, set\n `fb_usage` to 0 (APUs have no discrete framebuffer to report).\n\nThis approach is more robust than APU-specific checks because it:\n- Works for all scenarios where the VRAM manager is uninitialized (not just APUs),\n- Aligns with TTM's design by using its native helper function,\n- Preserves correct behavior for discrete GPUs (which have fully initialized\n `man->bdev` and pass the `ttm_resource_manager_used()` check).\n\nv4: use ttm_resource_manager_used(&adev->mman.vram_mgr.manager) instead of checking the adev->gmc.is_app_apu flag (Christian)"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c", "drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c", "drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "e70113b741ba253886cd71dbadfe3ea444bb2f5c", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1243e396148a65bb6c42a2b70fe43e50c16c494f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "43aa61c18a3a45042b098b7a1186ffb29364002c", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "070bdce18fb12a49eb9c421e57df17d2ad29bf5f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "883f309add55060233bf11c1ea6947140372920f", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c", "drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c", "drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c"], "versions": [{"version": "6.1.159", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.117", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.59", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.17.9", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.1.159"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.6.117"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.12.59"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.17.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/e70113b741ba253886cd71dbadfe3ea444bb2f5c"}, {"url": "https://git.kernel.org/stable/c/1243e396148a65bb6c42a2b70fe43e50c16c494f"}, {"url": "https://git.kernel.org/stable/c/43aa61c18a3a45042b098b7a1186ffb29364002c"}, {"url": "https://git.kernel.org/stable/c/070bdce18fb12a49eb9c421e57df17d2ad29bf5f"}, {"url": "https://git.kernel.org/stable/c/883f309add55060233bf11c1ea6947140372920f"}], "title": "drm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu: Fix NULL pointer dereference in VRAM logic for APU devices\n\nPreviously, APU platforms (and other scenarios with uninitialized VRAM managers)\ntriggered a NULL pointer dereference in `ttm_resource_manager_usage()`. The root\ncause is not that the `struct ttm_resource_manager *man` pointer itself is NULL,\nbut that `man->bdev` (the backing device pointer within the manager) remains\nuninitialized (NULL) on APUs\u2014since APUs lack dedicated VRAM and do not fully\nset up VRAM manager structures. When `ttm_resource_manager_usage()` attempts to\nacquire `man->bdev->lru_lock`, it dereferences the NULL `man->bdev`, 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->bdev` when it is\n NULL.\n\n3. **amdgpu_virt.c**: Modify the vf2pf (virtual function to physical function)\n data write path. Use `ttm_resource_manager_used()` to check validity: if the\n manager is usable, calculate `fb_usage` from VRAM usage; otherwise, set\n `fb_usage` to 0 (APUs have no discrete framebuffer to report).\n\nThis approach is more robust than APU-specific checks because it:\n- Works for all scenarios where the VRAM manager is uninitialized (not just APUs),\n- Aligns with TTM's design by using its native helper function,\n- Preserves correct behavior for discrete GPUs (which have fully initialized\n `man->bdev` and pass the `ttm_resource_manager_used()` check).\n\nv4: use ttm_resource_manager_used(&adev->mman.vram_mgr.manager) instead of checking the adev->gmc.is_app_apu flag (Christian)"}], "id": "CVE-2025-40288", "lastModified": "2025-12-06T22:15:57.067", "metrics": {}, "published": "2025-12-06T22:15:57.067", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/070bdce18fb12a49eb9c421e57df17d2ad29bf5f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1243e396148a65bb6c42a2b70fe43e50c16c494f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/43aa61c18a3a45042b098b7a1186ffb29364002c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/883f309add55060233bf11c1ea6947140372920f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e70113b741ba253886cd71dbadfe3ea444bb2f5c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}