udf: Fix off-by-one in volume descriptor sequence length

We pass one block beyond end of volume descriptor sequence into
process_sequence() as 'lastblock' instead of the last block of the
sequence. When the sequence is not terminated with TD descriptor, this
could lead to false errors due to invalid blocks in volume descriptor
sequence and thus unmountable volumes.

Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index f73239a9a97daa4a9046252323ef888b27691589..5c5d5fd513cce6081eca6ffd2f81b16ae3e25b21 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1658,7 +1658,7 @@ static noinline int udf_process_sequence(
                                next_e = le32_to_cpu(
                                        vdp->nextVolDescSeqExt.extLength);
                                next_e = next_e >> sb->s_blocksize_bits;
-                               next_e += next_s;
+                               next_e += next_s - 1;
                        }
                        break;
                case TAG_IDENT_IUVD: /* ISO 13346 3/10.4 */
@@ -1760,13 +1760,13 @@ static int udf_load_sequence(struct super_block *sb, struct buffer_head *bh,
        main_s = le32_to_cpu(anchor->mainVolDescSeqExt.extLocation);
        main_e = le32_to_cpu(anchor->mainVolDescSeqExt.extLength);
        main_e = main_e >> sb->s_blocksize_bits;
-       main_e += main_s;
+       main_e += main_s - 1;
 
        /* Locate the reserve sequence */
        reserve_s = le32_to_cpu(anchor->reserveVolDescSeqExt.extLocation);
        reserve_e = le32_to_cpu(anchor->reserveVolDescSeqExt.extLength);
        reserve_e = reserve_e >> sb->s_blocksize_bits;
-       reserve_e += reserve_s;
+       reserve_e += reserve_s - 1;
 
        /* Process the main & reserve sequences */
        /* responsible for finding the PartitionDesc(s) */