Use After Free Affecting kernel-default-base package, versions <5.3.18-150200.24.209.1.150200.9.109.1


Severity

Recommended
0.0
high
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (5th percentile)

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  • Snyk IDSNYK-SLES152-KERNELDEFAULTBASE-8443527
  • published29 Nov 2024
  • disclosed28 Nov 2024

Introduced: 28 Nov 2024

NewCVE-2022-48988  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.2 kernel-default-base to version 5.3.18-150200.24.209.1.150200.9.109.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default-base package and not the kernel-default-base package as distributed by SLES. See How to fix? for SLES:15.2 relevant fixed versions and status.

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

memcg: fix possible use-after-free in memcg_write_event_control()

memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too.

Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's.

Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type.

CVSS Scores

version 3.1