CVE-2024-43863: drm/vmwgfx: Fix a deadlock in dma buf fence polling
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.
Other sources
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— Launchpad
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-43863?
CVE-2024-43863 has not been specifically assigned a CVSS score, so its severity may vary based on the environment.
How do I fix CVE-2024-43863?
To fix CVE-2024-43863, update the Linux kernel to a patched version available for the affected distributions.
Which versions of Linux Kernel are affected by CVE-2024-43863?
CVE-2024-43863 affects Linux Kernel versions from 3.18 up to but not including 6.11-rc1, with specific ranges noted.
Is CVE-2024-43863 a remote vulnerability?
CVE-2024-43863 does not explicitly categorize itself as a remote vulnerability, but its impact may depend on system configuration.
Can CVE-2024-43863 cause system crashes?
CVE-2024-43863 addresses a deadlock issue, so it has the potential to lead to system hangs or crashes if not mitigated.