isofs: release buffer head before return

Release the buffer_head before returning error code in
do_isofs_readdir() and isofs_find_entry().

Fixes: 2deb1acc65 ("isofs: fix access to unallocated memory when reading corrupted filesystem")
Link: https://lore.kernel.org/r/20210118120455.118955-1-bianpan2016@163.com
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/isofs/dir.c

@@ -152,6 +152,7 @@ static int do_isofs_readdir(struct inode *inode, struct file *file,
 			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
 			       " in block %lu of inode %lu\n", block,
 			       inode->i_ino);
+			brelse(bh);
 			return -EIO;
 		}
 

fs/isofs/namei.c

@@ -102,6 +102,7 @@ isofs_find_entry(struct inode *dir, struct dentry *dentry,
 			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
 			       " in block %lu of inode %lu\n", block,
 			       dir->i_ino);
+			brelse(bh);
 			return 0;
 		}