CVE-2026-97900 drm/drm_exec: fix up contended obj when num_objects is 0
A local attacker can cause an infinite loop and system hang in the Linux kernel DRM subsystem by triggering contention with empty object arrays.
- 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-2026-97900?
CVE-2026-97900 is a denial of service vulnerability in Linux, published on 25 Sep 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/drm_exec: fix up contended obj when num_objects is 0
drm_exec_prepare_array() silently returns success without calling drm_exec_lock_contended() when num_objects is zero. This breaks the invariant upheld by drm_exec_lock_obj(), where every entry point into the locking sequence must first attempt to lock any previously contended object before proceeding.
Drivers that chain multiple drm_exec_prepare_array() calls per drm_exec_until_all_locked() iteration (e.g. amdgpu's userq signal/wait ioctls, which prepare separate read and write BO arrays) can pass an empty array for one of the two calls. If contention is hit while preparing the non-empty array, exec->contended is set and the loop retries; on retry, the empty-array call preceding it is a no-op that never clears exec->contended, so drm_exec_retry_on_contention() immediately jumps back to the top of the loop without ever reaching the call that would resolve the contention. This spins forever.
Fix it by having drm_exec_prepare_array() call drm_exec_lock_contended() directly when num_objects is zero, so a pending contended object dont loop infinitely.
Which versions are affected by CVE-2026-97900?
How do I fix CVE-2026-97900?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-97900 being exploited?
There is no known exploitation of CVE-2026-97900 in the wild and no public exploit code.
Sources
Also known as AZL-104286, BELL-CVE-2026-97900, DEBIAN-CVE-2026-97900, GHSA-fx27-pfff-j2g5, UBUNTU-CVE-2026-97900.