---
id: CVE-2026-68266
title: 'drm/xe: Hold a dma-buf reference for imported BOs'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/xe: Hold a dma-buf reference for imported BOs

  An imported dma-buf BO is created as a ttm_bo_type_sg BO whose
  reservation object is the exporter's dma_buf->resv. Th…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 <
    c22d65d62b3318e237c0e5b1177d90ab83d9fe06
  - >-
    Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 <
    c1954c66662de477a8f4309335b775f7b07bd28b
  - >-
    Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 <
    ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48
  - >-
    Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 <
    62775525a27c3b0d56382e08ba81ee2d322058b6
  - Linux 6.8
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:46:26.487807Z'
published: '2026-08-10'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:53:05.657Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-68266'
references:
  - url: 'https://git.kernel.org/stable/c/c22d65d62b3318e237c0e5b1177d90ab83d9fe06'
  - url: 'https://git.kernel.org/stable/c/c1954c66662de477a8f4309335b775f7b07bd28b'
  - url: 'https://git.kernel.org/stable/c/ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48'
  - url: 'https://git.kernel.org/stable/c/62775525a27c3b0d56382e08ba81ee2d322058b6'
tags:
  - cve.org
epss: 0.00134
epssPercentile: 0.026
ingestedAt: '2026-10-16T17:24:46.853Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

drm/xe: Hold a dma-buf reference for imported BOs

An imported dma-buf BO is created as a ttm_bo_type_sg BO whose
reservation object is the exporter's dma_buf->resv. The importer,
however, only takes a dma-buf reference after a successful
dma_buf_dynamic_attach(). Until then nothing keeps the exporter alive,
so if the exporter is freed while the BO still references its resv, a
later access to that resv is a use-after-free:

  Oops: general protection fault, probably for non-canonical address
        0x6b6b6b6b6b6b6b9c
  Workqueue: ttm ttm_bo_delayed_delete [ttm]
  RIP: 0010:mutex_can_spin_on_owner+0x3f/0xc0

This can be reached on two paths:

 - dma_buf_dynamic_attach() fails, or
 - ttm_bo_init_reserved() fails during BO creation.

In both cases the BO already has bo->base.resv pointing at the exporter
resv, and sg BOs are always torn down via ttm_bo_delayed_delete(), which
locks bo->base.resv asynchronously - potentially after the exporter has
been freed.

Take the dma-buf reference in xe_bo_init_locked(), before
ttm_bo_init_reserved(), so it also covers a creation failure there, and
release it in xe_ttm_bo_destroy(). The reference is held for the whole
BO lifetime, keeping the shared resv alive on every path.

v2:
  - Reworked the fix to avoid creating the imported sg BO before
    dma_buf_dynamic_attach() succeeds.
  - Attach with importer_priv == NULL and make invalidate_mappings ignore
    incomplete imports.

v3:
  - Dropped the xe-side reordering approach since importer_priv must be
    valid when dma_buf_dynamic_attach() publishes the attachment.
  - Per Christian's suggestion on the v1 thread, keyed the check on
    import_attach rather than removing the sg guard entirely.
  - Fixes both xe and amdgpu in a single TTM patch.

v4:
  - Moved import_attach check to after dma_resv_copy_fences() so fences
    are copied before returning for successful imports (Thomas).
  - Removed exporter-alive claim from commit message (Thomas).

v5:
  - Add drm/xe patch to keep imported sg BOs off the LRU before attach
    succeeds; the TTM fix alone is not sufficient for xe if the BO is
    already LRU-visible. (Thomas)
    v4 patch:
    https://patchwork.freedesktop.org/patch/736663/?series=169129&rev=2
  - Patch 1 (drm/ttm) carries Christian's Reviewed-by from v4.

v6:
  - Reworked the fix based on Thomas' suggestion. Instead of the TTM resv
    individualization (v1-v5) plus the xe off-LRU/placement handling (v5),
    just hold a dma-buf reference for the imported BO lifetime so the
    shared resv can never be freed while the BO still references it.
    Single xe patch, no TTM change. (Thomas)
  - Take the reference in xe_bo_init_locked() before ttm_bo_init_reserved()
    so a TTM creation failure is covered too (Thomas).
  - Dropped the v5 series (drm/ttm + drm/xe off-LRU); the off-LRU approach
    also regressed in CI BAT via ttm_bo_pipeline_gutting() creating a ghost
    BO that outlived the exporter.
    Link to v5: https://patchwork.freedesktop.org/series/169984/

v7:
  - Move changelog above --- so it stays in the commit message.
  - Reorder changelog entries oldest-to-newest. (Thomas)

(cherry picked from commit 3516f3fae6be35642f8f06f8a218da6425c0306a)

## Affected

- `Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 < c22d65d62b3318e237c0e5b1177d90ab83d9fe06`
- `Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 < c1954c66662de477a8f4309335b775f7b07bd28b`
- `Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 < ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48`
- `Linux >= dd08ebf6c3525a7ea2186e636df064ea47281987 < 62775525a27c3b0d56382e08ba81ee2d322058b6`
- `Linux 6.8`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.