CVE-2026-53062

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> dm cache policy smq: fix missing locks in invalidating cache blocks<br /> <br /> In passthrough mode, the policy invalidate_mapping operation is called<br /> simultaneously from multiple workers, thus it should be protected by a<br /> lock. Otherwise, we might end up with data races on the allocated blocks<br /> counter, or even use-after-free issues with internal data structures<br /> when doing concurrent writes.<br /> <br /> Note that the existing FIXME in smq_invalidate_mapping() doesn&amp;#39;t affect<br /> passthrough mode since migration tasks don&amp;#39;t exist there, but would need<br /> attention if supporting fast device shrinking via suspend/resume without<br /> target reloading.<br /> <br /> Reproduce steps:<br /> <br /> 1. Create a cache device consisting of 1024 cache entries<br /> <br /> dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"<br /> dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"<br /> dmsetup create corig --table "0 262144 linear /dev/sdc 262144"<br /> dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct<br /> dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \<br /> /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"<br /> <br /> 2. Populate the cache, and record the number of cached blocks<br /> <br /> fio --name=populate --filename=/dev/mapper/cache --rw=randwrite --bs=4k \<br /> --size=64m --direct=1<br /> nr_cached=$(dmsetup status cache | awk &amp;#39;{split($7, a, "/"); print a[1]}&amp;#39;)<br /> <br /> 3. Reload the cache into passthrough mode<br /> <br /> dmsetup suspend cache<br /> dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \<br /> /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"<br /> dmsetup resume cache<br /> <br /> 4. Write to the passthrough cache. By setting multiple jobs with I/O<br /> size equal to the cache block size, cache blocks are invalidated<br /> concurrently from different workers.<br /> <br /> fio --filename=/dev/mapper/cache --name=test --rw=randwrite --bs=64k \<br /> --direct=1 --numjobs=2 --randrepeat=0 --size=64m<br /> <br /> 5. Check if demoted matches cached block count. These numbers should<br /> match but may differ due to the data race.<br /> <br /> nr_demoted=$(dmsetup status cache | awk &amp;#39;{print $12}&amp;#39;)<br /> echo "$nr_cached, $nr_demoted"