CVE-2024-43863 drm/vmwgfx: Fix a deadlock in dma buf fence polling
A deadlock in the vmwgfx driver's fence polling can cause system stalls or denial of service, particularly affecting KDE users.
- 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-2024-43863?
CVE-2024-43863 is a medium-severity vulnerability in Linux kernel, published on 20 Aug 2024. 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/vmwgfx: Fix a deadlock in dma buf fence polling
Introduce a version of the fence ops that on release doesn't remove the fence from the pending list, and thus doesn't require a lock to fix poll->fence wait->fence unref deadlocks.
vmwgfx overwrites the wait callback to iterate over the list of all fences and update their status, to do that it holds a lock to prevent the list modifcations from other threads. The fence destroy callback both deletes the fence and removes it from the list of pending fences, for which it holds a lock.
dma buf polling cb unrefs a fence after it's been signaled: so the poll calls the wait, which signals the fences, which are being destroyed. The destruction tries to acquire the lock on the pending fences list which it can never get because it's held by the wait from which it was called.
Old bug, but not a lot of userspace apps were using dma-buf polling interfaces. Fix those, in particular this fixes KDE stalls/deadlock.
Weakness: CWE-667
Which versions are affected by CVE-2024-43863?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-43863?
Apply the vendor's patch.
Is CVE-2024-43863 being exploited?
There is no known exploitation of CVE-2024-43863 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-48507, BELL-CVE-2024-43863, DEBIAN-CVE-2024-43863, GHSA-f95q-fwq6-mx8w, ROOT-OS-DEBIAN-11-CVE-2024-43863, UBUNTU-CVE-2024-43863.