dm crypt: reject sector_size feature if device length is not aligned to it

If a crypt mapping uses optional sector_size feature, additional
restrictions to mapped device segment size must be applied in
constructor, otherwise the device activation will fail later.

Fixes: 8f0009a2 ("dm crypt: optionally support larger encryption sector size")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-crypt.c

@@ -2585,6 +2585,10 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar
 				ti->error = "Invalid feature value for sector_size";
 				return -EINVAL;
 			}
+			if (ti->len & ((cc->sector_size >> SECTOR_SHIFT) - 1)) {
+				ti->error = "Device size is not multiple of sector_size feature";
+				return -EINVAL;
+			}
 			cc->sector_shift = __ffs(cc->sector_size) - SECTOR_SHIFT;
 		} else if (!strcasecmp(opt_string, "iv_large_sectors"))
 			set_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags);