kernel/linux.git/drivers/md/dm-log.c, branch v6.6.141

dm log: fix out-of-bounds write due to region_count overflow

2026-05-23T11:03:11+00:00

[ Upstream commit c20e36b7631d83e7535877f08af8b0af72c44b1a ] The local variable region_count in create_log_context() is declared as unsigned int (32-bit), but dm_sector_div_up() returns sector_t (64-bit). When a device-mapper target has a sufficiently large ti->len with a small region_size, the division result can exceed UINT_MAX. The truncated value is then used to calculate bitset_size, causing clean_bits, sync_bits, and recovering_bits to be allocated far smaller than needed for the actual number of regions. Subsequent log operations (log_set_bit, log_clear_bit, log_test_bit) use region indices derived from the full untruncated region space, causing out-of-bounds writes to kernel heap memory allocated by vmalloc. This can be reproduced by creating a mirror target whose region_count overflows 32 bits: dmsetup create bigzero --table '0 8589934594 zero' dmsetup create mymirror --table '0 8589934594 mirror \ core 2 2 nosync 2 /dev/mapper/bigzero 0 \ /dev/mapper/bigzero 0' The status output confirms the truncation (sync_count=1 instead of 4294967297, because 0x100000001 was truncated to 1): $ dmsetup status mymirror 0 8589934594 mirror 2 254:1 254:1 1/4294967297 ... This leads to a kernel crash in core_in_sync: BUG: scheduling while atomic: (udev-worker)/9150/0x00000000 RIP: 0010:core_in_sync+0x14/0x30 [dm_log] CR2: 0000000000000008 Fixing recursive fault but reboot is needed! Fix by widening the local region_count to sector_t and adding an explicit overflow check before the value is assigned to lc->region_count. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Yuhao Jiang Signed-off-by: Junrui Luo Signed-off-by: Mikulas Patocka Signed-off-by: Sasha Levin

dm: replace -EEXIST with -EBUSY

2026-03-04T12:20:44+00:00

[ Upstream commit b13ef361d47f09b7aecd18e0383ecc83ff61057e ] The -EEXIST error code is reserved by the module loading infrastructure to indicate that a module is already loaded. When a module's init function returns -EEXIST, userspace tools like kmod interpret this as "module already loaded" and treat the operation as successful, returning 0 to the user even though the module initialization actually failed. This follows the precedent set by commit 54416fd76770 ("netfilter: conntrack: helper: Replace -EEXIST by -EBUSY") which fixed the same issue in nf_conntrack_helper_register(). Affected modules: * dm_cache dm_clone dm_integrity dm_mirror dm_multipath dm_pcache * dm_vdo dm-ps-round-robin dm_historical_service_time dm_io_affinity * dm_queue_length dm_service_time dm_snapshot Signed-off-by: Daniel Gomez Signed-off-by: Mikulas Patocka Signed-off-by: Sasha Levin

dm io: Support IO priority

2024-03-26T22:20:13+00:00

[ Upstream commit 6e5f0f6383b4896c7e9b943d84b136149d0f45e9 ] Some IO will dispatch from kworker with different io_context settings than the submitting task, we may need to specify a priority to avoid losing priority. Add IO priority parameter to dm_io() and update all callers. Co-developed-by: Yibin Ding Signed-off-by: Yibin Ding Signed-off-by: Hongyu Jin Reviewed-by: Eric Biggers Reviewed-by: Mikulas Patocka Signed-off-by: Mike Snitzer Stable-dep-of: b4d78cfeb304 ("dm-integrity: align the outgoing bio in integrity_recheck") Signed-off-by: Sasha Levin

dm: remove unnecessary (void*) conversions

2023-04-11T16:01:01+00:00

Pointer variables of void * type do not require type cast. Signed-off-by: Yu Zhe Signed-off-by: Mike Snitzer

dm log: avoid multiple line dereference

2023-02-14T19:23:07+00:00