ext4: avoid potential buffer_head leak in __ext4_new_inode()

If a group is marked EXT4_GROUP_INFO_IBITMAP_CORRUPT after it's inode
bitmap buffer_head was successfully verified, then __ext4_new_inode()
will get a valid inode_bitmap_bh of a corrupted group from
ext4_read_inode_bitmap() in which case inode_bitmap_bh misses a release.
Hnadle "IS_ERR(inode_bitmap_bh)" and group corruption separately like
how ext4_free_inode() does to avoid buffer_head leak.

Fixes: 9008a58 ("ext4: make the bitmap read routines return real error codes")
Signed-off-by: Kemeng Shi <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: Kemeng Shi

fs/ext4/ialloc.c

@@ -1054,12 +1054,13 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
 		brelse(inode_bitmap_bh);
 		inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
 		/* Skip groups with suspicious inode tables */
-		if (((!(sbi->s_mount_state & EXT4_FC_REPLAY))
-		     && EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) ||
-		    IS_ERR(inode_bitmap_bh)) {
+		if (IS_ERR(inode_bitmap_bh)) {
 			inode_bitmap_bh = NULL;
 			goto next_group;
 		}
+		if (!(sbi->s_mount_state & EXT4_FC_REPLAY) &&
+		    EXT4_MB_GRP_IBITMAP_CORRUPT(grp))
+			goto next_group;
 
 repeat_in_this_group:
 		ret2 = find_inode_bit(sb, group, inode_bitmap_bh, &ino);