CVE-2026-68266: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9jm7-867x-hm4j",
  "modified" : "2026-08-14T00:31:54Z",
  "published" : "2026-08-10T15:33:43Z",
  "aliases" : [ "CVE-2026-68266" ],
  "details" : "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)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-68266"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/62775525a27c3b0d56382e08ba81ee2d322058b6"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/c1954c66662de477a8f4309335b775f7b07bd28b"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/c22d65d62b3318e237c0e5b1177d90ab83d9fe06"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-10T13:20:15Z"
  }
}