CIFS: Fix ERR_PTR dereference in cifs_get_root

commit 5b980b01 upstream.

move it to the beginning of the loop.
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/cifs/cifsfs.c

@@ -566,6 +566,12 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
 		struct inode *dir = dentry->d_inode;
 		struct dentry *child;
 
+		if (!dir) {
+			dput(dentry);
+			dentry = ERR_PTR(-ENOENT);
+			break;
+		}
+
 		/* skip separators */
 		while (*s == sep)
 			s++;
@@ -581,10 +587,6 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
 		mutex_unlock(&dir->i_mutex);
 		dput(dentry);
 		dentry = child;
-		if (!dentry->d_inode) {
-			dput(dentry);
-			dentry = ERR_PTR(-ENOENT);
-		}
 	} while (!IS_ERR(dentry));
 	_FreeXid(xid);
 	kfree(full_path);