Out-of-bounds Read Affecting kernel-rt-kvm package, versions <0:4.18.0-348.rt7.130.el8


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTKVM-4104223
  • published26 Jul 2021
  • disclosed26 May 2021

Introduced: 26 May 2021

CVE-2021-33200  (opens in a new tab)
CWE-125  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade RHEL:8 kernel-rt-kvm to version 0:4.18.0-348.rt7.130.el8 or higher.
This issue was patched in RHSA-2021:4140.

NVD Description

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

kernel/bpf/verifier.c in the Linux kernel through 5.12.7 enforces incorrect limits for pointer arithmetic operations, aka CID-bb01a1bba579. This can be abused to perform out-of-bounds reads and writes in kernel memory, leading to local privilege escalation to root. In particular, there is a corner case where the off reg causes a masking direction change, which then results in an incorrect final aux->alu_limit.

CVSS Scores

version 3.1