Affected: Alpaquita:stream: linux-lts

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

dm-pcache: validate seg_id fields from persistent memory

cache_pos_decode(), cache_key_decode() and the last-kset branches of cache_replay(), the writeback worker and the GC worker take a cache segment id from the cache device metadata and index cache->segments[] with it without checking it against cache->n_segs. That metadata is only CRC-protected with a fixed public seed, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range value forms a wild pcache_cache_segment pointer that is dereferenced and written through -- an out-of-bounds read and write driven by on-disk data.

Add cache_seg_id_valid() and reject an out-of-range id at each decode site, failing the operation with -EIO instead of indexing past the array. Bound the id against the initialized-segment count (cache_info.n_segs) rather than the physical device total. A forged cache_info.n_segs below seg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed structs whose data pointer is NULL, so a forged id in that window would still be dereferenced. A later patch guarantees cache_info.n_segs <= seg_num, and a driver-created cache sets the two equal, so valid images are unaffected.

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

dm-pcache: validate seg_id fields from persistent memory

cache_pos_decode(), cache_key_decode() and the last-kset branches of cache_replay(), the writeback worker and the GC worker take a cache segment id from the cache device metadata and index cache->segments[] with it without checking it against cache->n_segs. That metadata is only CRC-protected with a fixed public seed, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range value forms a wild pcache_cache_segment pointer that is dereferenced and written through -- an out-of-bounds read and write driven by on-disk data.

Add cache_seg_id_valid() and reject an out-of-range id at each decode site, failing the operation with -EIO instead of indexing past the array. Bound the id against the initialized-segment count (cache_info.n_segs) rather than the physical device total. A forged cache_info.n_segs below seg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed structs whose data pointer is NULL, so a forged id in that window would still be dereferenced. A later patch guarantees cache_info.n_segs <= seg_num, and a driver-created cache sets the two equal, so valid images are unaffected.

kernel-devel-7.2.7-1.1 on GA media

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 118 more

In the Linux kernel, the following vulnerability has been resolved: dm-pcache: validate seg_id fields from persistent memory cache_pos_decode(), cache_key_decode() and the last-kset branches of cache_replay(), the writeback worker and the GC worker take a cache segment id from the cache device metadata and index cache->segments[] with it without checking it against cache->n_segs. That metadata is only CRC-protected with a fixed public seed, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range value forms a wild pcache_cache_segment pointer that is dereferenced and written through -- an out-of-bounds read and write driven by on-disk data. Add cache_seg_id_valid() and reject an out-of-range id at each decode site, failing the operation with -EIO instead of indexing past the array. Bound the id against the initialized-segment count (cache_info.n_segs) rather than the physical device total. A forged cache_info.n_segs below seg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed structs whose data pointer is NULL, so a forged id in that window would still be dereferenced. A later patch guarantees cache_info.n_segs <= seg_num, and a driver-created cache sets the two equal, so valid images are unaffected.

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel möglicherweise ausnutzen, um Berechtigungen zu erweitern, Sicherheitsmaßnahmen zu umgehen, Daten offenzulegen oder zu manipulieren, den Speicher zu beschädigen, Denial-of-Service-Zustände zu verursachen oder andere, nicht näher spezifizierte Angriffe durchzuführen.