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Improper Input Validation The advisory has been revoked - it doesn't affect any version of package kernel-doc  (opens in a new tab)

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0.04% (6th percentile)

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  • Snyk IDSNYK-CENTOS8-KERNELDOC-6338983
  • published29 Feb 2024
  • disclosed28 Feb 2024
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Introduced: 28 Feb 2024

CVE-2021-46990  (opens in a new tab)
CWE-20  (opens in a new tab)

Amendment

The Centos security team deemed this advisory irrelevant for Centos:8.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-doc package and not the kernel-doc package as distributed by Centos.

In the Linux kernel, the following vulnerability has been resolved:

powerpc/64s: Fix crashes when toggling entry flush barrier

The entry flush mitigation can be enabled/disabled at runtime via a debugfs file (entry_flush), which causes the kernel to patch itself to enable/disable the relevant mitigations.

However depending on which mitigation we're using, it may not be safe to do that patching while other CPUs are active. For example the following crash:

sleeper[15639]: segfault (11) at c000000000004c20 nip c000000000004c20 lr c000000000004c20

Shows that we returned to userspace with a corrupted LR that points into the kernel, due to executing the partially patched call to the fallback entry flush (ie. we missed the LR restore).

Fix it by doing the patching under stop machine. The CPUs that aren't doing the patching will be spinning in the core of the stop machine logic. That is currently sufficient for our purposes, because none of the patching we do is to that code or anywhere in the vicinity.