Deadlock Affecting kernel-debuginfo package, versions <0:4.14.343-259.562.amzn2
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Test your applications- Snyk ID SNYK-AMZN2-KERNELDEBUGINFO-7247725
- published 12 Jun 2024
- disclosed 11 Mar 2024
Introduced: 11 Mar 2024
CVE-2023-52486 Open this link in a new tabHow to fix?
Upgrade Amazon-Linux:2 kernel-debuginfo to version 0:4.14.343-259.562.amzn2 or higher.
This issue was patched in ALAS2-2024-2549.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-debuginfo package and not the kernel-debuginfo package as distributed by Amazon-Linux.
See How to fix? for Amazon-Linux:2 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.
References
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-52486
- https://git.kernel.org/stable/c/376e21a9e4c2c63ee5d8d3aa74be5082c3882229
- https://git.kernel.org/stable/c/62f2e79cf9f4f47cc9dea9cebdf58d9f7b5695e0
- https://git.kernel.org/stable/c/9dd334a8245011ace45e53298175c7b659edb3e7
- https://git.kernel.org/stable/c/b4af63da9d94986c529d74499fdfe44289acd551
- https://git.kernel.org/stable/c/bfd0feb1b109cb63b87fdcd00122603787c75a1a
- https://git.kernel.org/stable/c/cb4daf271302d71a6b9a7c01bd0b6d76febd8f0c
- https://git.kernel.org/stable/c/d7afdf360f4ac142832b098b4de974e867cc063c
- https://git.kernel.org/stable/c/f55261469be87c55df13db76dc945f6bcd825105
- https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
- https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html