NULL Pointer Dereference Affecting kernel package, versions <0:4.14.232-176.381.amzn2


Severity

Recommended
0.0
medium
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-AMZN2-KERNEL-6457490
  • published19 Mar 2024
  • disclosed26 Feb 2024

Introduced: 26 Feb 2024

CVE-2021-46904  (opens in a new tab)
CWE-476  (opens in a new tab)
First added by Snyk

How to fix?

Upgrade Amazon-Linux:2 kernel to version 0:4.14.232-176.381.amzn2 or higher.
This issue was patched in ALAS2-2021-1636.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel package and not the kernel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

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

net: hso: fix null-ptr-deref during tty device unregistration

Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref.

The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number.

Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call.

CVSS Scores

version 3.1