Use After Free Affecting kernel-obs-build package, versions <5.14.21-150400.24.128.1


Severity

Recommended
medium

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-SLES154-KERNELOBSBUILD-7692038
  • published16 Aug 2024
  • disclosed15 Aug 2024

Introduced: 15 Aug 2024

CVE-2022-48822  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.4 kernel-obs-build to version 5.14.21-150400.24.128.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-obs-build package and not the kernel-obs-build package as distributed by SLES. See How to fix? for SLES:15.4 relevant fixed versions and status.

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

usb: f_fs: Fix use-after-free for epfile

Consider a case where ffs_func_eps_disable is called from ffs_func_disable as part of composition switch and at the same time ffs_epfile_release get called from userspace. ffs_epfile_release will free up the read buffer and call ffs_data_closed which in turn destroys ffs->epfiles and mark it as NULL. While this was happening the driver has already initialized the local epfile in ffs_func_eps_disable which is now freed and waiting to acquire the spinlock. Once spinlock is acquired the driver proceeds with the stale value of epfile and tries to free the already freed read buffer causing use-after-free.

Following is the illustration of the race:

  CPU1                                  CPU2

ffs_func_eps_disable epfiles (local copy) ffs_epfile_release ffs_data_closed if (last file closed) ffs_data_reset ffs_data_clear ffs_epfiles_destroy spin_lock dereference epfiles

Fix this races by taking epfiles local copy & assigning it under spinlock and if epfiles(local) is null then update it in ffs->epfiles then finally destroy it. Extending the scope further from the race, protecting the ep related structures, and concurrent accesses.

CVSS Scores

version 3.1