CVE-2025-21694: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix softlockup in __read_vmcore (part 2) Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes. In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck. The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough. Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups.

Affected products

• Linux Linux Kernel: from 4.19.317, before 4.20 (fixed in 4.20); from 5.4.279, before 5.4.290 (fixed in 5.4.290); from 5.10.221, before 5.10.234 (fixed in 5.10.234); from 5.15.162, before 5.15.177 (fixed in 5.15.177); from 6.1.95, before 6.1.127 (fixed in 6.1.127); from 6.6.35, before 6.6.74 (fixed in 6.6.74); …

Published 2025-02-12. Last modified 2026-06-17.