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CVE-2026-98521

Linux: drm/i915: fix incorrect RCU teardown order

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.21%Chance of exploitation activity in the next 30 days, higher than 11% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in4d4ca84213327da1f84ef7af3946dea6b14c5d88Also 2dd0190e397ec6468095fd3e80e79276a7361449CVE List
Published18 Oct 2026Updated 19 Oct 2026CVE List

What fixes it

  • 4d4ca84213327da1f84ef7af3946dea6b14c5d88LinuxCVE List
  • 2dd0190e397ec6468095fd3e80e79276a7361449LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

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

drm/i915: fix incorrect RCU teardown order

i915_gem_busy_ioctl uses dma_resv_for_each_fence_unlocked() to iterate over the fences in an GEM object without holding a reference but only the RCU read side lock.

What can happen here is that the GEM object is destroyed concurrently while i915_gem_busy_ioctl is still running. This won't free the GEM objects memory, but still drops all the dma_fence references.

Now when dma_resv_for_each_fence_unlocked() sees a destroyed dma_fence it assumes that a new fence list was installed and re-starts the loop.

But in the case of a destroyed GEM object a new fence list is never installed, only the old one freed and therefore the iteration never finishes resulting in an endless loop.

The solution is to drop the fence references only after the RCU grace period.

The fixes tag is not necessary the patch introducing the problem, but the one making it so worse that we need to address it.

This problem was pointed out by Sashiko-bot.

(cherry picked from commit 5113479556025093bf8133bb2dcaa33be2d50921)

Text from CVE List

Affected versions 14

  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before 4d4ca84213327da1f84ef7af3946dea6b14c5d88CVE List
  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before c53db9cc245219af6b528ca022a17ebfa91d80baCVE List
  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before b12e041aedcf9fa77c6002a49f07eb20d0521b86CVE List
  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before cc890d3f1b15bf6481dc7270fba0b4fbba572813CVE List
  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before 2dd0190e397ec6468095fd3e80e79276a7361449CVE List
  • Linuxaffected: 912ff2ebd695c582ca4cebf833ad73a378a99f23 before d2da6696e0c4e60414706e607029d0bb0330c67eCVE List
  • Linuxaffected: 5.17CVE List
  • Linuxunaffected: all versions before 5.17CVE List
  • Linuxunaffected: 6.1.189 through 6.1.*CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.55 through 6.18.*CVE List
  • Linuxunaffected: 7.2.9 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 6