CVE-2025-38241

/// Technical description

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

mm/shmem, swap: fix softlockup with mTHP swapin

Following softlockup can be easily reproduced on my test machine with:

echo always > /sys/kernel/mm/transparent_hugepage/hugepages-64kB/enabled

swapon /dev/zram0 # zram0 is a 48G swap device

mkdir -p /sys/fs/cgroup/memory/test

echo 1G > /sys/fs/cgroup/test/memory.max

echo $BASHPID > /sys/fs/cgroup/test/cgroup.procs

while true; do

dd if=/dev/zero of=/tmp/test.img bs=1M count=5120

cat /tmp/test.img > /dev/null

rm /tmp/test.img

done

Then after a while:

watchdog: BUG: soft lockup - CPU#0 stuck for 763s! [cat:5787]

Modules linked in: zram virtiofs

CPU: 0 UID: 0 PID: 5787 Comm: cat Kdump: loaded Tainted: G L 6.15.0.orig-gf3021d9246bc-dirty #118 PREEMPT(voluntary)·

Tainted: [L]=SOFTLOCKUP

Hardware name: Red Hat KVM/RHEL-AV, BIOS 0.0.0 02/06/2015

RIP: 0010:mpol_shared_policy_lookup+0xd/0x70

Code: e9 b8 b4 ff ff 31 c0 c3 cc cc cc cc 90 90 90 90 90

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References