diff options
| author | Benjamin Marzinski <bmarzins@redhat.com> | 2026-07-02 21:43:39 -0400 |
|---|---|---|
| committer | Mikulas Patocka <mpatocka@redhat.com> | 2026-07-08 22:33:20 +0200 |
| commit | 9743132a41f4d9d0e54c5f2adcb821b04796bab1 (patch) | |
| tree | a19689846e822a1f81c0a004c920b9d99982c281 /drivers/md | |
| parent | 8cdeaa50eae8dad34885515f62559ee83e7e8dda (diff) | |
dm-log: fix a bitset_size overflow on 32bit machines
Commit c20e36b7631d ("dm log: fix out-of-bounds write due to
region_count overflow") made sure that region_count could fit in an
unsigned int. But the bitmap memory isn't allocated based on
region_count. It uses bitset_size (a size_t variable). The first step of
calculating bitset_size is to set it to region_count, rounded up to a
multiple of BITS_PER_LONG. If region_size is less than BITS_PER_LONG
smaller than UINT_MAX, it will get rounded up to 2^32. On a 32bit
architecture, this will make bitset_size wrap around to 0 and fail,
despite region_count being valid.
Since bitset_size gets divided by 8, it can hold any valid region_count.
It just needs a special case to handle the rollover. If it is 0, the
value rolled over, and bitset size should be set to the number of bytes
needed to hold 2^32 bits.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: c20e36b7631d ("dm log: fix out-of-bounds write due to region_count overflow")
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-log.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c index d316757a328b..2ddeb4250c59 100644 --- a/drivers/md/dm-log.c +++ b/drivers/md/dm-log.c @@ -425,6 +425,9 @@ static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti, */ bitset_size = dm_round_up(region_count, BITS_PER_LONG); bitset_size >>= BYTE_SHIFT; + /* Handle dm_round_up rollover on 32-bit systems */ + if (!bitset_size) + bitset_size = 1UL << (BITS_PER_LONG - BYTE_SHIFT); lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits); |