{"id":"CVE-2026-68266","revision":"d62b81fd8cab496e9c475215c40dedc2","records":[{"revision":"d62b81fd8cab496e9c475215c40dedc2","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-68266","aliases":[],"title":"drm/xe: Hold a dma-buf reference for imported BOs","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: Hold a dma-buf reference for imported BOs\n\nAn imported dma-buf BO is created as a ttm_bo_type_sg BO whose\nreservation object is the exporter's dma_buf->resv. The importer,\nhowever, only takes a dma-buf reference after a successful\ndma_buf_dynamic_attach(). Until then nothing keeps the exporter alive,\nso if the exporter is freed while the BO still references its resv, a\nlater access to that resv is a use-after-free:\n\n  Oops: general protection fault, probably for non-canonical address\n        0x6b6b6b6b6b6b6b9c\n  Workqueue: ttm ttm_bo_delayed_delete [ttm]\n  RIP: 0010:mutex_can_spin_on_owner+0x3f/0xc0\n\nThis can be reached on two paths:\n\n - dma_buf_dynamic_attach() fails, or\n - ttm_bo_init_reserved() fails during BO creation.\n\nIn both cases the BO already has bo->base.resv pointing at the exporter\nresv, and sg BOs are always torn down via ttm_bo_delayed_delete(), which\nlocks bo->base.resv asynchronously - potentially after the exporter has\nbeen freed.\n\nTake the dma-buf reference in xe_bo_init_locked(), before\nttm_bo_init_reserved(), so it also covers a creation failure there, and\nrelease it in xe_ttm_bo_destroy(). The reference is held for the whole\nBO lifetime, keeping the shared resv alive on every path.\n\nv2:\n  - Reworked the fix to avoid creating the imported sg BO before\n    dma_buf_dynamic_attach() succeeds.\n  - Attach with importer_priv == NULL and make invalidate_mappings ignore\n    incomplete imports.\n\nv3:\n  - Dropped the xe-side reordering approach since importer_priv must be\n    valid when dma_buf_dynamic_attach() publishes the attachment.\n  - Per Christian's suggestion on the v1 thread, keyed the check on\n    import_attach rather than removing the sg guard entirely.\n  - Fixes both xe and amdgpu in a single TTM patch.\n\nv4:\n  - Moved import_attach check to after dma_resv_copy_fences() so fences\n    are copied before returning for successful imports (Thomas).\n  - Removed exporter-alive claim from commit message (Thomas).\n\nv5:\n  - Add drm/xe patch to keep imported sg BOs off the LRU before attach\n    succeeds; the TTM fix alone is not sufficient for xe if the BO is\n    already LRU-visible. (Thomas)\n    v4 patch:\n    https://patchwork.freedesktop.org/patch/736663/?series=169129&rev=2\n  - Patch 1 (drm/ttm) carries Christian's Reviewed-by from v4.\n\nv6:\n  - Reworked the fix based on Thomas' suggestion. Instead of the TTM resv\n    individualization (v1-v5) plus the xe off-LRU/placement handling (v5),\n    just hold a dma-buf reference for the imported BO lifetime so the\n    shared resv can never be freed while the BO still references it.\n    Single xe patch, no TTM change. (Thomas)\n  - Take the reference in xe_bo_init_locked() before ttm_bo_init_reserved()\n    so a TTM creation failure is covered too (Thomas).\n  - Dropped the v5 series (drm/ttm + drm/xe off-LRU); the off-LRU approach\n    also regressed in CI BAT via ttm_bo_pipeline_gutting() creating a ghost\n    BO that outlived the exporter.\n    Link to v5: https://patchwork.freedesktop.org/series/169984/\n\nv7:\n  - Move changelog above --- so it stays in the commit message.\n  - Reorder changelog entries oldest-to-newest. (Thomas)\n\n(cherry picked from commit 3516f3fae6be35642f8f06f8a218da6425c0306a)","state":0,"publishedAt":"2026-08-10T12:01:41.28+00:00","modifiedAt":"2026-10-19T20:58:58.924+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/gpu/drm/xe/xe_bo.c\",\n                        \"drivers/gpu/drm/xe/xe_bo.h\",\n                        \"drivers/gpu/drm/xe/xe_bo_types.h\",\n                        \"drivers/gpu/drm/xe/xe_dma_buf.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"dd08ebf6c3525a7ea2186e636df064ea47281987\",\n                            \"lessThan\": \"c22d65d62b3318e237c0e5b1177d90ab83d9fe06\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"dd08ebf6c3525a7ea2186e636df064ea47281987\",\n                            \"lessThan\": \"c1954c66662de477a8f4309335b775f7b07bd28b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"dd08ebf6c3525a7ea2186e636df064ea47281987\",\n                            \"lessThan\": \"ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"dd08ebf6c3525a7ea2186e636df064ea47281987\",\n                            \"lessThan\": \"62775525a27c3b0d56382e08ba81ee2d322058b6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/gpu/drm/xe/xe_bo.c\",\n                        \"drivers/gpu/drm/xe/xe_bo.h\",\n                        \"drivers/gpu/drm/xe/xe_bo_types.h\",\n                        \"drivers/gpu/drm/xe/xe_dma_buf.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.8\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.8\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.103\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.42\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.6\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/c22d65d62b3318e237c0e5b1177d90ab83d9fe06","https://git.kernel.org/stable/c/c1954c66662de477a8f4309335b775f7b07bd28b","https://git.kernel.org/stable/c/ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48","https://git.kernel.org/stable/c/62775525a27c3b0d56382e08ba81ee2d322058b6"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68266","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-68266","identifiers":["CVE-2026-68266"]},"retained":false,"historicalAffected":[]}],"coverage":[]}