{"id":"CVE-2026-98999","title":"drm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin\n\nxe_bo_pin_external() and xe_bo_unpin_external() maintain the bo's\npinned_link list membership …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < 3a11adcfd9a2de74d405bd3e8c4d7a1b328e4684","Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < b3eaff982839e5c22912d604cd8e7748cece8d63","Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < cf238c067eaae1cbfb00738e29219b9568d2313e","Linux 6.8"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T12:20:19.451Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98999","references":[{"url":"https://git.kernel.org/stable/c/3a11adcfd9a2de74d405bd3e8c4d7a1b328e4684"},{"url":"https://git.kernel.org/stable/c/b3eaff982839e5c22912d604cd8e7748cece8d63"},{"url":"https://git.kernel.org/stable/c/cf238c067eaae1cbfb00738e29219b9568d2313e"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T13:24:55.542Z","slug":"CVE-2026-98999","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin\n\nxe_bo_pin_external() and xe_bo_unpin_external() maintain the bo's\npinned_link list membership in xe->pinned.late.external, based on\nwhether the current call is the outermost pin or the final unpin.\nHowever, the same external bo's pin_count can also be raised and\nlowered directly by __xe_pin_fb_vma()/__xe_unpin_fb_vma(), which pin\nthe bo as a display scanout buffer without going through\nxe_bo_pin_external()/xe_bo_unpin_external() at all, and have no\nnotion of, or ownership over, pinned_link.\n\nIf a bo is pinned both externally (e.g. dma-buf export) and as an fb,\nand the external unpin happens first, xe_bo_unpin_external() correctly\nobserves pin_count > 1 and leaves the bo on pinned_link. When the fb\nunpin later performs the true last unpin (pin_count 1 -> 0), it never\ntouches pinned_link, leaving the bo linked on xe->pinned.late.external\nindefinitely. Once the bo is subsequently freed, this stale list entry\npoints into freed memory, corrupting the list and risking a\nuse-after-free the next time the list is walked or spliced.\n\nThe backup object pin/unpin sites in xe_bo_notifier_prepare_pinned()/\nxe_bo_notifier_unprepare_pinned() have the same bypass characteristic,\nthough they never add their bo to a pinned list, so are not affected\nby this particular list-corruption issue.\n\nMove the pinned_link removal into xe_bo_account_unpin(), which already\nruns on every unpin path (kernel, external, framebuffer, backup\nobject) right before the true 1 -> 0 pin_count transition. Since\nlist_del_init() only operates on the node itself, this removal is\nlist-agnostic and safe to perform regardless of which list (external\nor kernel_bo_present) the bo happens to be linked on, or which code\npath is performing the final unpin. Drop the now-redundant explicit\nlist_del_init() calls in xe_bo_unpin_external() and xe_bo_unpin().\n\nv2:\n- New patch\n\nv3:\n- Rebased on changes to previous patch.\n\n(cherry picked from commit ca58d36a1f93af586ee93b340c9f9fd81312cc01)\n\n## Affected\n\n- `Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < 3a11adcfd9a2de74d405bd3e8c4d7a1b328e4684`\n- `Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < b3eaff982839e5c22912d604cd8e7748cece8d63`\n- `Linux >= 44e694958b95395bd1c41508c88c8ca141bf9bd7 < cf238c067eaae1cbfb00738e29219b9568d2313e`\n- `Linux 6.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}