CVE-2026-98521 drm/i915: fix incorrect RCU teardown order
A race condition in the i915 DRM driver causes an infinite loop during GEM object destruction, leading to local denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98521?
CVE-2026-98521 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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)
Which versions are affected by CVE-2026-98521?
How do I fix CVE-2026-98521?
Apply the vendor's patch.
Is CVE-2026-98521 being exploited?
There is no known exploitation of CVE-2026-98521 in the wild and no public exploit code.
Sources
Also known as AZL-109427, BELL-CVE-2026-98521, DEBIAN-CVE-2026-98521, GHSA-7hvf-3rfm-fg86, UBUNTU-CVE-2026-98521.