kernel/git/stable/linux.git/drivers/md, branch linux-6.18.y

dm: fix resume-vs-remove race

2026-09-11T09:49:12+00:00

commit 44b43ec132f1cf3275ecc182d0c82f50c3c4c3d5 upstream. If the user issues the resume ioctl and the remove ioctl at the same time, it may be possible that the device is resumed after it is suspended in __dm_destroy. The result is that the table is destroyed without calling the postsuspend method. Dm targets expect that they may be removed only after the postsuspend method method was called. If we break this expectation, it can cause misbehavior in various targets. For example - in the dm-integrity target, the reboot notifier is not unregistered, leading to use-after-free. Fix this bug by refusing to resume if the device is being destroyed. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

dm: fix race when loading and unloading a table

2026-09-11T09:49:11+00:00

commit 5380c7f6335cc6d77eb77d065105e81155c4d9d3 upstream. If the userspace calls two concurrent table load ioctls and one of them succeeds and the other fails, there is a race condition because dm_setup_md_queue walks &md->table_devices without any lock. If the walk races with dm_table_destroy -> free_devices -> dm_put_table_device, there is access to invalid memory. Fix this race by extending the lock over the list walk. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

dm-pcache: fix use-after-free and invalid seg operations in kset_replay()

2026-09-07T15:22:57+00:00

commit c2e894eac398b258f12fdec73ed6ba081047f7b3 upstream. In kset_replay, when key->seg_gen is stale (key->seg_gen < key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then key->cache_pos.cache_seg is accessed as the argument to cache_seg_get(). This is a use-after-free on the freed key memory. Although mempool recycled memory is not immediately reclaimed or overwritten in practice, this is still a potential UAF bug. Additionally, for expired invalid keys, setting the cache->seg_map bit and calling cache_seg_get() is unreasonable since the corresponding segment data is no longer valid. Fix both issues by moving cache_seg_get() and __set_bit() after the gen check, so they only execute for valid keys, and using continue to skip invalid keys. Cc: stable@vger.kernel.org Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Signed-off-by: Jianyun Gao Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: fix implicit u8 truncation of gc_percent in message handler

2026-09-07T15:22:57+00:00

commit fb9e17287a4ea1cbbcedc77e6866978ecc2a7b55 upstream. When setting gc_percent via message, kstrtoul parses the input into an unsigned long, which is then implicitly truncated to u8 when passed to pcache_cache_set_gc_percent(). For example, value 266 (0x10A) silently truncates to 10 (0x0A), successfully bypassing the > 90 upper bound check in pcache_cache_set_gc_percent(), and setting a different value than the user intended. Use kstrtou8 directly instead of kstrtoul, so that overflow values are properly rejected. Cc: stable@vger.kernel.org Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Signed-off-by: Jianyun Gao Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: only hand out initialized cache segments

2026-09-07T15:22:57+00:00

commit 2df0fc042e299bae3c0f60ea5cd2af9285658e9f upstream. get_cache_segment() scans the segment map up to cache->n_segs, the physical device segment count, but cache_segs_init() only initializes the first cache_info->n_segs segments. A crafted image with cache_info->n_segs smaller than the device count leaves the remaining pcache_cache_segment structs zeroed (segment.data == NULL), and the allocator can hand one to cache_kset_close(), which writes through the returned segment's data pointer with no NULL check. Bound the allocator's search to cache_info->n_segs so only initialized segments are ever returned. A conforming cache sets n_segs equal to the device segment count, so this rejects nothing legitimate. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: detect a cycle in the last-kset chain during replay

2026-09-07T15:22:57+00:00

commit 16c3b3a326e70f246a605b3dc27b7f83ba4743e3 upstream. cache_replay() follows the on-media last-kset chain by next_cache_seg_id with no cond_resched(). A forged chain that points back into a segment it has already visited makes the replay loop follow it forever. Cap the last-kset hops at cache->n_segs; a valid chain visits each segment at most once. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: clamp the tail kset read to the segment data region

2026-09-07T15:22:57+00:00

commit becf07e2b0053027495ecd671b1f82fb2e615f68 upstream. The tail-kset read in cache_replay(), the writeback worker and the GC worker bounds its length by PCACHE_SEG_SIZE - seg_off, the raw segment size rather than the data region. A tail near the segment end reads past the segment data into the following control area. Clamp the read to cache_seg_remain(), the data region. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: bound the persisted tail-position offset

2026-09-07T15:22:57+00:00

commit d1898576090a10d2ac2715218a652e78fb65a6b0 upstream. cache_pos_decode() takes the persisted key_tail and dirty_tail seg_off from the cache device and addresses within the segment with it. A seg_off at or past the segment data_size, controllable by whoever supplies the device (CAP_SYS_ADMIN), reads past the segment data. Reject a decoded seg_off that is not below the segment data_size. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: validate on-media seg_num against the cache device size

2026-09-07T15:22:57+00:00

commit 62d92e45abe9e087370f9fc5d876b95673aced34 upstream. seg_num is read from the crc32c-only superblock, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls it. It sizes cache->segments[] and is the value every later on-media segment id is bounded against, yet it is never checked against the device. Because cache_dev->mapping is the direct map of the pmem, CACHE_DEV_SEGMENT() for a segment id past the device resolves to ordinary kernel memory beyond the mapping; a new-cache init reaching such an id has cache_seg_init() -> cache_dev_zero_range() memset() 12 KiB over that memory -- an out-of-bounds write into the kernel heap at table load. A zero seg_num makes the segment allocations ZERO_SIZE_PTR. Reject a seg_num that is zero, larger than the device can hold, or larger than PCACHE_CACHE_SEGS_MAX before it is used. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm-pcache: validate kset key_num and intra-segment bounds

2026-09-07T15:22:57+00:00

commit f11deb032fd84081e7831cffcba895d893054a22 upstream. Two more fields decoded from the cache device go unbounded. The kset key_num drives cache_kset_crc() and the replay loop in cache_replay(), the writeback worker and the GC worker, but only the magic and a fixed-seed CRC are checked first, so a non-last kset whose key_num exceeds the PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare. A key's intra-segment offset and length in cache_key_decode() are taken verbatim, so a key running past its segment is replayed into the cache tree and the data CRC check and every later read hit then copy adjacent persistent memory into the caller's bio -- an out-of-bounds read that leaks to user space. Both fields are controlled by whoever supplies the cache device (CAP_SYS_ADMIN); the CRC seed is public. Add kset_onmedia_valid() to bound key_num before any kset read, and reject a key whose offset plus length, computed in 64 bits, exceeds the segment data_size. Valid metadata is unaffected. Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman