udf: Add checks to not underflow sector_t
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/udf/super.c b/fs/udf/super.c
index b9dc6ad..3c2d35d 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -731,13 +731,18 @@
sector_t last[6];
int i;
struct udf_sb_info *sbi = UDF_SB(sb);
+ int last_count = 0;
- last[0] = lastblock;
- last[1] = last[0] - 1;
- last[2] = last[0] + 1;
- last[3] = last[0] - 2;
- last[4] = last[0] - 150;
- last[5] = last[0] - 152;
+ last[last_count++] = lastblock;
+ if (lastblock >= 1)
+ last[last_count++] = lastblock - 1;
+ last[last_count++] = lastblock + 1;
+ if (lastblock >= 2)
+ last[last_count++] = lastblock - 2;
+ if (lastblock >= 150)
+ last[last_count++] = lastblock - 150;
+ if (lastblock >= 152)
+ last[last_count++] = lastblock - 152;
/* according to spec, anchor is in either:
* block 256
@@ -745,7 +750,7 @@
* lastblock
* however, if the disc isn't closed, it could be 512 */
- for (i = 0; i < ARRAY_SIZE(last); i++) {
+ for (i = 0; i < last_count; i++) {
if (last[i] >= sb->s_bdev->bd_inode->i_size >>
sb->s_blocksize_bits)
continue;