PT-2026-51955 · Linux · Linux
Published
2026-06-24
·
Updated
2026-06-24
·
CVE-2026-53061
None
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In the Linux kernel, the following vulnerability has been resolved:
dm cache: fix dirty mapping checking in passthrough mode switching
As mentioned in commit 9b1cc9f251af ("dm cache: share cache-metadata
object across inactive and active DM tables"), dm-cache assumed table
reload occurs after suspension, while LVM's table preload breaks this
assumption. The dirty mapping check for passthrough mode was designed
around this assumption and is performed during table creation, causing
the check to fail with preload while metadata updates are ongoing. This
risks loading dirty mappings into passthrough mode, resulting in data
loss.
Reproduce steps:
- Create a writeback cache with zero migration threshold to produce dirty mappings
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 writeback smq
2 migration threshold 0"
- Preload a table in passthrough mode
dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"
- Write to the first cache block to make it dirty
fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k
--direct=1 --size=64k
- Resume the inactive table. Now it's possible to load the dirty block into passthrough mode.
dmsetup resume cache
Fix by moving the checks to the preresume phase to support table
preloading. Also remove the unused function dm cache metadata all clean.
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Related Identifiers
Affected Products
Linux