CVE-2026-53062 dm cache policy smq: fix missing locks in invalidating cache blocks
A race condition in the Linux kernel's dm cache policy allows concurrent invalidation to cause use-after-free, potentially leading to code execution or system crashes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53062?
CVE-2026-53062 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
dm cache policy smq: fix missing locks in invalidating cache blocks
In passthrough mode, the policy invalidate_mapping operation is called simultaneously from multiple workers, thus it should be protected by a lock. Otherwise, we might end up with data races on the allocated blocks counter, or even use-after-free issues with internal data structures when doing concurrent writes.
Note that the existing FIXME in smq_invalidate_mapping() doesn't affect passthrough mode since migration tasks don't exist there, but would need attention if supporting fast device shrinking via suspend/resume without target reloading.
Reproduce steps:
1. Create a cache device consisting of 1024 cache entries
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
2. Populate the cache, and record the number of cached blocks
fio --name=populate --filename=/dev/mapper/cache --rw=randwrite --bs=4k \ --size=64m --direct=1 nr_cached=$(dmsetup status cache | awk '{split($7, a, "/"); print a[1]}')
3. Reload the cache into passthrough mode
dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache
4. Write to the passthrough cache. By setting multiple jobs with I/O size equal to the cache block size, cache blocks are invalidated concurrently from different workers.
fio --filename=/dev/mapper/cache --name=test --rw=randwrite --bs=64k \ --direct=1 --numjobs=2 --randrepeat=0 --size=64m
5. Check if demoted matches cached block count. These numbers should match but may differ due to the data race.
nr_demoted=$(dmsetup status cache | awk '{print $12}') echo "$nr_cached, $nr_demoted"
Which versions are affected by CVE-2026-53062?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53062?
Apply the vendor's patch.
Is CVE-2026-53062 being exploited?
There is no known exploitation of CVE-2026-53062 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53062, DEBIAN-CVE-2026-53062, GHSA-4j2m-gfqm-629p, ROOT-OS-DEBIAN-11-CVE-2026-53062, ROOT-OS-DEBIAN-12-CVE-2026-53062, ROOT-OS-UBUNTU-2204-CVE-2026-53062 and 2 more.