[PATCH 5.10 68/84] dm mirror log: round up region bitmap size to BITS_PER_LONG

Greg Kroah-Hartman
2022-06-20T13:14:59Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit 85e123c27d5cbc22cfdc01de1e2ca1d9003a02d0 upstream.

The code in dm-log rounds up bitset_size to 32 bits. It then uses
find_next_zero_bit_le on the allocated region. find_next_zero_bit_le
accesses the bitmap using unsigned long pointers. So, on 64-bit
architectures, it may access 4 bytes beyond the allocated size.

Fix this bug by rounding up bitset_size to BITS_PER_LONG.

This bug was found by running the lvm2 testsuite with kasan.

Fixes: 29121bd0b00e ("[PATCH] dm mirror log: bitset_size fix")
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-log.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -415,8 +415,7 @@ static int create_log_context(struct dm_
/*
* Work out how many "unsigned long"s we need to hold the bitset.
*/
- bitset_size = dm_round_up(region_count,
- sizeof(*lc->clean_bits) << BYTE_SHIFT);
+ bitset_size = dm_round_up(region_count, BITS_PER_LONG);
bitset_size >>= BYTE_SHIFT;

lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);