Deadlock Affecting kernel-tools package, versions <0:4.18.0-553.16.1.el8_10


Severity

Recommended
high

Based on CentOS security rating.

Threat Intelligence

EPSS
0.04% (15th percentile)

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  • Snyk IDSNYK-CENTOS8-KERNELTOOLS-6424407
  • published14 Mar 2024
  • disclosed29 Feb 2024

Introduced: 29 Feb 2024

CVE-2023-52486  (opens in a new tab)
CWE-833  (opens in a new tab)

How to fix?

Upgrade Centos:8 kernel-tools to version 0:4.18.0-553.16.1.el8_10 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-tools package and not the kernel-tools package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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 drm_mode_page_flip_ioctl() 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 CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I saw that drm_closefb() 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.

CVSS Scores

version 3.1