CVE-2023-52486: drm: Don't unref the same fb many times by mistake due to deadlock handling
In the Linux kernel, the following vulnerability has been resolved:
drm: Don't unref the same fb many times by mistake due to deadlock handling
If we get a deadlock after the fb lookup in drmmodepageflipioctl() we proceed to unref the fb and then retry the whole thing from the top. But we forget to reset the fb pointer back to NULL, and so if we then get another error during the retry, before the fb lookup, we proceed the unref the same fb again without having gotten another reference. The end result is that the fb will (eventually) end up being freed while it's still in use.
Reset fb to NULL once we've unreffed it to avoid doing it again until we've done another fb lookup.
This turned out to be pretty easy to hit on a DG2 when doing async flips (and CONFIGDEBUGWWMUTEXSLOWPATH=y). The first symptom I saw that drmclosefb() simply got stuck in a busy loop while walking the framebuffer list. Fortunately I was able to convince it to oops instead, and from there it was easier to track down the culprit.
Other sources
In the Linux kernel, the following vulnerability has been resolved:
drm: Don't unref the same fb many times by mistake due to deadlock handling
The Linux kernel CVE team has assigned CVE-2023-52486 to this issue.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/20240229155245.1571576-27-lee@kernel.org/T/#u
— Red Hat
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2023-52486?
CVE-2023-52486 has been assigned a medium severity rating due to potential denial of service implications.
How do I fix CVE-2023-52486?
To mitigate CVE-2023-52486, update the Linux kernel to version 4.19.307, 5.4.269, 5.10.210, 5.15.149, 6.1.76, 6.6.15, 6.7.3, or 6.8.
What versions of the Linux kernel are affected by CVE-2023-52486?
CVE-2023-52486 affects Linux kernel versions prior to 4.19.307, between versions 4.20 and 5.4.269, 5.5 to 5.10.210, 5.11 to 5.15.149, 5.16 to 6.1.76, 6.2 to 6.6.15, and 6.7 to 6.7.3.
Is CVE-2023-52486 specific to any distribution?
CVE-2023-52486 impacts multiple distributions of the Linux kernel, notably those provided by Red Hat and Debian.
What type of vulnerability is CVE-2023-52486?
CVE-2023-52486 is a resource management issue that can lead to a denial of service due to improper reference counting in the Direct Rendering Manager.