Deadlock Affecting kernel6.18-modules-extra-common package, versions <1:6.18.48-107.148.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.21% (10th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618MODULESEXTRACOMMON-20247669
  • published29 Sept 2026
  • disclosed22 Aug 2026

Introduced: 22 Aug 2026

CVE-2026-74593  (opens in a new tab)
CWE-833  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-modules-extra-common to version 1:6.18.48-107.148.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3139.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-modules-extra-common package and not the kernel6.18-modules-extra-common package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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

sched_ext: Take cgroup_lock() first in scx_cgroup_lock()

scx_cgroup_lock() write-locks scx_cgroup_ops_rwsem and then takes cgroup_lock(), which can deadlock through kernfs:

scx enable/disable cgroup rmdir cpu.weight write


                         cgroup_lock()

percpu_down_write(rwsem) cgroup_lock() kernfs_get_active() percpu_down_read(rwsem) kernfs_drain()

The enable path waits for the rmdir to release cgroup_mutex. The rmdir, deactivating the cpu controller's files, waits in kernfs_drain() for the write's active reference. The write, in scx_group_set_weight(), waits for the rwsem behind the pending writer.

Take cgroup_lock() first. The set_* paths take no cgroup locks inside the read side, so a pending write-lock then only waits for read sections that always run to completion, and no dependency from the rwsem back to cgroup_mutex remains.

CVSS Base Scores

version 3.1