CVE-2024-35791 Affecting kernel-rt package, versions <0:5.14.0-284.75.1.rt14.360.el9_2


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (12th percentile)

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  • Snyk IDSNYK-RHEL9-KERNELRT-7562565
  • published25 Jul 2024
  • disclosed17 May 2024

Introduced: 17 May 2024

CVE-2024-35791  (opens in a new tab)
First added by Snyk

How to fix?

Upgrade RHEL:9 kernel-rt to version 0:5.14.0-284.75.1.rt14.360.el9_2 or higher.
This issue was patched in RHSA-2024:4831.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt package and not the kernel-rt package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

KVM: SVM: Flush pages under kvm->lock to fix UAF in svm_register_enc_region()

Do the cache flush of converted pages in svm_register_enc_region() before dropping kvm->lock to fix use-after-free issues where region and/or its array of pages could be freed by a different task, e.g. if userspace has __unregister_enc_region_locked() already queued up for the region.

Note, the "obvious" alternative of using local variables doesn't fully resolve the bug, as region->pages is also dynamically allocated. I.e. the region structure itself would be fine, but region->pages could be freed.

Flushing multiple pages under kvm->lock is unfortunate, but the entire flow is a rare slow path, and the manual flush is only needed on CPUs that lack coherency for encrypted memory.

CVSS Scores

version 3.1