Improper Control of a Resource Through its Lifetime Affecting kernel-rt-debug-kvm package, versions <0:4.18.0-553.16.1.rt7.357.el8_10


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTDEBUGKVM-7037406
  • published23 May 2024
  • disclosed22 May 2024

Introduced: 22 May 2024

CVE-2021-47491  (opens in a new tab)
CWE-664  (opens in a new tab)

How to fix?

Upgrade RHEL:8 kernel-rt-debug-kvm to version 0:4.18.0-553.16.1.rt7.357.el8_10 or higher.
This issue was patched in RHSA-2024:5102.

NVD Description

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

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

mm: khugepaged: skip huge page collapse for special files

The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2].

This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface.

[shy828301@gmail.com: fix vm_file check [3]]

CVSS Scores

version 3.1