{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80633","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-26T14:34:25.776Z","datePublished":"2026-08-28T06:48:48.372Z","dateUpdated":"2026-08-29T06:21:32.731Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-29T06:21:32.731Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Take dma_resv lock before dma_buf_unpin() in release path\n\ndma_buf_unpin() requires the caller to hold the exporter's dma_resv\nlock:\n\n  void dma_buf_unpin(struct dma_buf_attachment *attach)\n  {\n          ...\n          dma_resv_assert_held(dmabuf->resv);\n          ...\n  }\n\niopt_release_pages() calls dma_buf_unpin() without taking that lock,\nso every iommufd_ioas_destroy()/iommufd_ioas_unmap() that releases\nthe last reference on a DMABUF-backed iopt_pages triggers a WARN.\nThis was hit while running tools/testing/selftests/iommu/iommufd:\n\n  WARNING: drivers/dma-buf/dma-buf.c:1137 at dma_buf_unpin+0x62/0x70\n  RIP: 0010:dma_buf_unpin+0x62/0x70\n  Call Trace:\n   <TASK>\n   dma_buf_unpin+0x62/0x70\n   iopt_release_pages+0xe4/0x190\n   iopt_unmap_iova_range+0x1c7/0x290\n   iopt_unmap_all+0x1a/0x30\n   iommufd_ioas_destroy+0x1d/0x50\n   iommufd_fops_release+0x93/0x150\n   __fput+0xfc/0x2c0\n   __x64_sys_close+0x3d/0x80\n   do_syscall_64+0x65/0x180\n   </TASK>\n\nTake the dma_resv lock around dma_buf_unpin() in iopt_release_pages(),\nmatching the iopt_map_dmabuf() convention. dma_buf_detach() acquires the\nreservation lock internally, so it must remain outside the locked region."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only via local syscalls on /dev/iommu or VFIO-compat iommufd: open, IOMMU_IOAS_MAP_FILE with a dma-buf fd, then IOMMU_IOAS_UNMAP/close triggers iopt_release_pages()->dma_buf_unpin(); no network or packet handler is involved.\nAC:L - Every teardown of the last dma-buf-backed iopt_pages deterministically hits dma_buf_unpin() without dma_resv; an attacker also controls concurrent invalidate/revoke via IOMMU_IOAS_UNMAP and dma_buf_invalidate_mappings (selftest revoke or VFIO PCI dmabuf revoke).\nPR:L - No init-namespace root or special capability is required for the IOAS map/unmap path once a process can open iommufd (0660) and hold a compatible dma-buf fd, as in cloud GPU/VFIO passthrough tenants or iommufd selftests.\nUI:N - Exploitation requires no victim interaction; the attacker programmatically creates the IOAS dma-buf mapping and drives unmap/close and optional concurrent revoke through their own file descriptors and ioctl calls.\nS:C - Missing dma_resv locking during dma-buf unpin/detach races dma_buf_invalidate_mappings and can leave stale IOMMU IOVA-to-physical mappings or permit buffer movement while DMA views remain, breaking the IOMMU/DMA isolation boundary.\nC:H - Concurrent dma_resv-protected invalidation during unpin without the reservation lock can race teardown of iopt_pages/dmabuf attachments and yield kernel heap use-after-free or stale mapping visibility exploitable for arbitrary kernel memory read.\nI:H - Racing unpin without dma_resv against invalidate/revoke can leave IOMMU page tables pointing at repinned/moved exporter pages, giving a device DMA write primitive to attacker-influenced physical memory and enabling control-flow corruption.\nA:H - The missing lock triggers dma_resv_assert_held WARN on every dma-buf IOAS unmap/destroy (reproduced in iommufd selftests), and concurrent teardown races can provoke kernel oops/panic or wedge GPU/VFIO+iommufd workloads."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/iommufd/pages.c"],"versions":[{"version":"8c5f9645c3893f0db679d9affe4fe4e665b990dd","lessThan":"cc69d0332421fd2943b66dbe5e597bf4fd5af126","status":"affected","versionType":"git"},{"version":"8c5f9645c3893f0db679d9affe4fe4e665b990dd","lessThan":"e745cd2c749e557c14a15ac931761c3f58c24489","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/iommu/iommufd/pages.c"],"versions":[{"version":"7.1","status":"affected"},{"version":"0","lessThan":"7.1","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","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:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/cc69d0332421fd2943b66dbe5e597bf4fd5af126"},{"url":"https://git.kernel.org/stable/c/e745cd2c749e557c14a15ac931761c3f58c24489"}],"title":"iommufd: Take dma_resv lock before dma_buf_unpin() in release path","x_generator":{"engine":"bippy-1.2.0"}}}}