From: Eric Biggers <ebiggers@xxxxxxxxxx> sb_mac() verifies that the superblock + MAC don't exceed 512 bytes. Because the superblock is currently 64 bytes, this really verifies mac_size <= 448. This confuses smatch into thinking that mac_size may be as large as 448, which is inconsistent with the later code that assumes the MAC fits in a buffer of size HASH_MAX_DIGESTSIZE (64). In fact mac_size <= HASH_MAX_DIGESTSIZE is guaranteed by the crypto API, as that is the whole point of HASH_MAX_DIGESTSIZE. But, let's be defensive and explicitly check for this. This suppresses the false positive smatch warning. It does not fix an actual bug. Reported-by: kernel test robot <lkp@xxxxxxxxx> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Closes: https://lore.kernel.org/r/202409061401.44rtN1bh-lkp@xxxxxxxxx/ Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- drivers/md/dm-integrity.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index 51e6964c13054..3b9738787c855 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -489,11 +489,12 @@ static int sb_mac(struct dm_integrity_c *ic, bool wr) int r; unsigned int mac_size = crypto_shash_digestsize(ic->journal_mac); __u8 *sb = (__u8 *)ic->sb; __u8 *mac = sb + (1 << SECTOR_SHIFT) - mac_size; - if (sizeof(struct superblock) + mac_size > 1 << SECTOR_SHIFT) { + if (sizeof(struct superblock) + mac_size > 1 << SECTOR_SHIFT || + mac_size > HASH_MAX_DIGESTSIZE) { dm_integrity_io_error(ic, "digest is too long", -EINVAL); return -EINVAL; } desc->tfm = ic->journal_mac; base-commit: 8d8d276ba2fb5f9ac4984f5c10ae60858090babc -- 2.46.0
