SB20261029103 - Race condition in Linux kernel fsnotify connector teardown in fs/notify/mark.c, particularly fsnotify_destroy_marks()

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-99175)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause a denial of service by triggering a kernel NULL pointer dereference.

The vulnerability exists due to a race condition in the Linux kernel fsnotify connector teardown when new notification marks are inserted while fsnotify_destroy_marks() destroys existing marks. A local user can race an inotify watch re-addition and an fdinfo read against connector teardown to trigger a call to igrab(NULL), causing a kernel crash.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/36ebddca56b9d8993d6dc984fdecc748ee1f5e06
• https://git.kernel.org/stable/c/472589eacdf10b5f9bd10b333957ed5291b2544b
• https://git.kernel.org/stable/c/952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1