udf: Verify inode link counts before performing rename

During rename, we are updating link counts of various inodes either when rename deletes target or when moving directory across directories. Verify involved link counts are sane so that we don't trip warnings in VFS. Reported-by: [email protected] Signed-off-by: Jan Kara <[email protected]>
tiwai · Nov 26, 2024 · 6756af9 · 6756af9
1 parent c556690
commit 6756af9
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
@@ -791,8 +791,18 @@ static int udf_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 			retval = -ENOTEMPTY;
 			if (!empty_dir(new_inode))
 				goto out_oiter;
+			retval = -EFSCORRUPTED;
+			if (new_inode->i_nlink != 2)
+				goto out_oiter;
 		}
+		retval = -EFSCORRUPTED;
+		if (old_dir->i_nlink < 3)
+			goto out_oiter;
 		is_dir = true;
+	} else if (new_inode) {
+		retval = -EFSCORRUPTED;
+		if (new_inode->i_nlink < 1)
+			goto out_oiter;
 	}
 	if (is_dir && old_dir != new_dir) {
 		retval = udf_fiiter_find_entry(old_inode, &dotdot_name,