dm crypt: don't overallocate the integrity tag space

Mikulas Patocka · snitm · commit ff0c129d3b5e · 2019-02-11T12:06:48.000-05:00
bio_sectors() returns the value in the units of 512-byte sectors (no matter what the real sector size of the device). dm-crypt multiplies bio_sectors() by on_disk_tag_size to calculate the space allocated for integrity tags. If dm-crypt is running with sector size larger than 512b, it allocates more data than is needed. Device Mapper trims the extra space when passing the bio to dm-integrity, so this bug didn't result in any visible misbehavior. But it must be fixed to avoid wasteful memory allocation for the block integrity payload. Fixes: ef43aa3 ("dm crypt: add cryptographic data integrity protection (authenticated encryption)") Cc: stable@vger.kernel.org # 4.12+ Reported-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
@@ -932,7 +932,7 @@ static int dm_crypt_integrity_io_alloc(struct dm_crypt_io *io, struct bio *bio)
 	if (IS_ERR(bip))
 		return PTR_ERR(bip);
 
-	tag_len = io->cc->on_disk_tag_size * bio_sectors(bio);
+	tag_len = io->cc->on_disk_tag_size * (bio_sectors(bio) >> io->cc->sector_shift);
 
 	bip->bip_iter.bi_size = tag_len;
 	bip->bip_iter.bi_sector = io->cc->start + io->sector;
