Description
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: 1. 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" 2. 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" 3. 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 4. 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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < c2e86f647561fcf5e1c6eba7d75e9e0c4299c94daffected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 5c98a3f1d7a554c9e920aa31daf92af6b5bbb8ccaffected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 1443c32f24d6d8bcdf4beceef2afc09290b98717affected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 12105c7f18375d7615dad7605d89eadae7eb12a6affected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < bd5a2c1018938e6b32670728bdb32a3f0efff00faffected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 21c503d60a257e54ca3ac58e2721bd24501d5bdeaffected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 01b22656d8a68dbeae59f8b80866e7b11936b20aaffected2ee57d587357f0d752af6c2e3e46434a74b1bee3 to < 322586745bd1a0e5f3559fd1635fdeb4dbd1d6b8affected
Linux Linux
Default version status: affected
3.13affected0 to < 3.13unaffected5.10.258 to ≤ 5.10.*unaffected5.15.209 to ≤ 5.15.*unaffected6.1.175 to ≤ 6.1.*unaffected6.6.141 to ≤ 6.6.*unaffected6.12.91 to ≤ 6.12.*unaffected6.18.33 to ≤ 6.18.*unaffected7.0.10 to ≤ 7.0.*unaffected7.1 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/c2e86f647561fcf5e1c6eba7d75e9e0c4299c94d ↗
- https://git.kernel.org/stable/c/5c98a3f1d7a554c9e920aa31daf92af6b5bbb8cc ↗
- https://git.kernel.org/stable/c/1443c32f24d6d8bcdf4beceef2afc09290b98717 ↗
- https://git.kernel.org/stable/c/12105c7f18375d7615dad7605d89eadae7eb12a6 ↗
- https://git.kernel.org/stable/c/bd5a2c1018938e6b32670728bdb32a3f0efff00f ↗
- https://git.kernel.org/stable/c/21c503d60a257e54ca3ac58e2721bd24501d5bde ↗
- https://git.kernel.org/stable/c/01b22656d8a68dbeae59f8b80866e7b11936b20a ↗
- https://git.kernel.org/stable/c/322586745bd1a0e5f3559fd1635fdeb4dbd1d6b8 ↗