CVE-2025-38282: kernfs: Relax constraint in draining guard

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-10 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: kernfs: Relax constraint in draining guard The active reference lifecycle provides the break/unbreak mechanism but the active reference is not truly active after unbreak -- callers don't use it afterwards but it's important for proper pairing of kn->active counting. Assuming this mechanism is in place, the WARN check in kernfs_should_drain_open_files() is too sensitive -- it may transiently catch those (rightful) callers between kernfs_unbreak_active_protection() and kernfs_put_active() as found out by Chen Ridong: kernfs_remove_by_name_ns kernfs_get_active // active=1 __kernfs_remove // active=0x80000002 kernfs_drain ... wait_event //waiting (active == 0x80000001) kernfs_break_active_protection // active = 0x80000001 // continue kernfs_unbreak_active_protection // active = 0x80000002 ... kernfs_should_drain_open_files // warning occurs kernfs_put_active To avoid the false positives (mind panic_on_warn) remove the check altogether. (This is meant as quick fix, I think active reference break/unbreak may be simplified with larger rework.)

Affected products

Debian Linux: 11.0
Linux kernel: from 6.1 before 6.1.142; from 6.2 before 6.6.94; from 6.7 before 6.12.34; from 6.13 before 6.15.3 — fixed in 6.1.142, 6.12.34, 6.15.3, 6.6.94

How to fix

Upgrade to a fixed version: Linux kernel 6.1.142, 6.12.34, 6.15.3, 6.6.94. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2025-38282 or the next vulnerability affects your stack