CVE-2023-53728 Affecting kernel-tools-devel package, versions <0:4.14.322-244.536.amzn2


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-AMZN2-KERNELTOOLSDEVEL-13843507
  • published6 Nov 2025
  • disclosed22 Oct 2025

Introduced: 22 Oct 2025

NewCVE-2023-53728  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 kernel-tools-devel to version 0:4.14.322-244.536.amzn2 or higher.
This issue was patched in ALAS2-2023-2268.

NVD Description

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

posix-timers: Ensure timer ID search-loop limit is valid

posix_timer_add() tries to allocate a posix timer ID by starting from the cached ID which was stored by the last successful allocation.

This is done in a loop searching the ID space for a free slot one by one. The loop has to terminate when the search wrapped around to the starting point.

But that's racy vs. establishing the starting point. That is read out lockless, which leads to the following problem:

CPU0 CPU1 posix_timer_add() start = sig->posix_timer_id; lock(hash_lock); ... posix_timer_add() if (++sig->posix_timer_id < 0) start = sig->posix_timer_id; sig->posix_timer_id = 0;

So CPU1 can observe a negative start value, i.e. -1, and the loop break never happens because the condition can never be true:

if (sig->posix_timer_id == start) break;

While this is unlikely to ever turn into an endless loop as the ID space is huge (INT_MAX), the racy read of the start value caught the attention of KCSAN and Dmitry unearthed that incorrectness.

Rewrite it so that all id operations are under the hash lock.

CVSS Base Scores

version 3.1