From patchwork Sun Jan 25 21:57:40 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Weinberger X-Patchwork-Id: 5705841 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id B9648C058D for ; Sun, 25 Jan 2015 21:58:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 060BE200E0 for ; Sun, 25 Jan 2015 21:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D6B0200DE for ; Sun, 25 Jan 2015 21:58:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751639AbbAYV5w (ORCPT ); Sun, 25 Jan 2015 16:57:52 -0500 Received: from mail.sigma-star.at ([95.130.255.111]:14385 "EHLO mail.sigma-star.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbbAYV5w (ORCPT ); Sun, 25 Jan 2015 16:57:52 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.sigma-star.at (Postfix) with ESMTP id 24CEB24F8003; Sun, 25 Jan 2015 22:57:48 +0100 (CET) X-Virus-Scanned: amavisd-new at mail.sigma-star.at Received: from linux.site (richard.vpn.sigmapriv.at [10.3.0.5]) by mail.sigma-star.at (Postfix) with ESMTPSA id 1555524F8002; Sun, 25 Jan 2015 22:57:47 +0100 (CET) From: Richard Weinberger To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Richard Weinberger Subject: [PATCH] fs: Detect API misuse of i_op->lookup Date: Sun, 25 Jan 2015 22:57:40 +0100 Message-Id: <1422223060-8561-1-git-send-email-richard@nod.at> X-Mailer: git-send-email 2.2.2 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Hunting down a refcount issue in an out-of-tree filesystem uncovered that its lookup function directly returned the dentry which was passed to it. Add a BUG_ON() to detect such misuse in future. Signed-off-by: Richard Weinberger --- fs/namei.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/namei.c b/fs/namei.c index bc35b02..f8ccae6 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1370,6 +1370,7 @@ static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, old = dir->i_op->lookup(dir, dentry, flags); if (unlikely(old)) { + BUG_ON(old == dentry); dput(dentry); dentry = old; }