CVE-2025-21694 Information

Description

In the Linux kernel the following vulnerability has been resolved:

fs/proc: fix softlockup in __read_vmcore (part 2)

Since commit 5cbcb62dddf5 (s/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.

Reference

https://git.kernel.org/stable/c/649b266606bc413407ce315f710c8ce8a88ee30a https://git.kernel.org/stable/c/65c367bd9d4f43513c7f837df5753bea9561b836 https://git.kernel.org/stable/c/80828540dad0757b6337c6561d49c81038f38d87 https://git.kernel.org/stable/c/80da29deb88a3a907441fc35bb7bac309f31e713 https://git.kernel.org/stable/c/84c4ed15626574c9ac6c1039ba9c137a77bcc7f2 https://git.kernel.org/stable/c/a5a2ee8144c3897d37403a69118c3e3dc5713958 https://git.kernel.org/stable/c/cbc5dde0a461240046e8a41c43d7c3b76d5db952