NULL Pointer Dereference Affecting kernel-rt-devel package, versions <0:4.18.0-372.9.1.rt7.166.el8


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (11th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTDEVEL-8166038
  • published8 Oct 2024
  • disclosed24 May 2024

Introduced: 24 May 2024

CVE-2021-47556  (opens in a new tab)
CWE-476  (opens in a new tab)
First added by Snyk

How to fix?

Upgrade RHEL:8 kernel-rt-devel to version 0:4.18.0-372.9.1.rt7.166.el8 or higher.
This issue was patched in RHSA-2022:1975.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-devel package and not the kernel-rt-devel 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:

ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce()

ethtool_set_coalesce() now uses both the .get_coalesce() and .set_coalesce() callbacks. But the check for their availability is buggy, so changing the coalesce settings on a device where the driver provides only one of the callbacks results in a NULL pointer dereference instead of an -EOPNOTSUPP.

Fix the condition so that the availability of both callbacks is ensured. This also matches the netlink code.

Note that reproducing this requires some effort - it only affects the legacy ioctl path, and needs a specific combination of driver options:

  • have .get_coalesce() and .coalesce_supported but no .set_coalesce(), or
  • have .set_coalesce() but no .get_coalesce(). Here eg. ethtool doesn't cause the crash as it first attempts to call ethtool_get_coalesce() and bails out on error.

CVSS Scores

version 3.1