ext4: make sanity check in mballoc more strict

The sanity check in mb_find_extent() only checked that returned extent does not extend past blocksize * 8, however it should not extend past EXT4_CLUSTERS_PER_GROUP(sb). This can happen when clusters_per_group < blocksize * 8 and the tail of the bitmap is not properly filled by 1s which happened e.g. when ancient kernels have grown the filesystem. Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]> Cc: [email protected]
niw · Apr 6, 2019 · 31562b9 · 31562b9
1 parent fb20375
commit 31562b9
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
@@ -1539,7 +1539,7 @@ static int mb_find_extent(struct ext4_buddy *e4b, int block,
 		ex->fe_len += 1 << order;
 	}
 
-	if (ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3))) {
+	if (ex->fe_start + ex->fe_len > EXT4_CLUSTERS_PER_GROUP(e4b->bd_sb)) {
 		/* Should never happen! (but apparently sometimes does?!?) */
 		WARN_ON(1);
 		ext4_error(e4b->bd_sb, "corruption or bug in mb_find_extent "