Sensitive Information Uncleared Before Release Affecting kernel-rt-debug-kvm package, versions <0:4.18.0-513.5.1.rt7.307.el8_9


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

Exploit Maturity
Mature
EPSS
0.06% (25th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTDEBUGKVM-5425306
  • published17 Apr 2023
  • disclosed12 Apr 2023

Introduced: 12 Apr 2023

CVE-2023-1998  (opens in a new tab)
CWE-226  (opens in a new tab)
CWE-385  (opens in a new tab)
CWE-200  (opens in a new tab)

How to fix?

Upgrade RHEL:8 kernel-rt-debug-kvm to version 0:4.18.0-513.5.1.rt7.307.el8_9 or higher.
This issue was patched in RHSA-2023:6901.

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.

The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line.

This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.

CVSS Scores

version 3.1