From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC29BC33CA9 for ; Tue, 14 Jan 2020 06:59:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87141207E0 for ; Tue, 14 Jan 2020 06:59:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="bwSScmx9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728901AbgANG7e (ORCPT ); Tue, 14 Jan 2020 01:59:34 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:57750 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728680AbgANG7e (ORCPT ); Tue, 14 Jan 2020 01:59:34 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00E6wuax189199; Tue, 14 Jan 2020 06:59:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=Um3aq13bt3KE8FaQoSHBOGx9xF1pyNNvuGHu3EV01Lg=; b=bwSScmx96s4yKtSNq2SZAalf38tHkEjLxLXLH0i7GgzsalBbDpDbuafNPtg9OBNw5hHD +Wnqy3cZbhidEUkZpVIuSO+O5p3AshrjC8HTQekJ4Egk7cov7XSfWPxkX+Xq6Sv/Y2JO xeRojrUAJyP2rFn4hCvDwkTawdb7rhsRrrfUuylEjLqmoltt9pGiSuXxIwc7YmOqF/Yu KZl5Yq7PWzxhpz4TZi4UK9aTsNaDgBGn6je5Emo5QjGOqXwCgieyKqAgzDnvHJxznHhF IMl/cdc8vk8m+ufDSsbmp4OsurT2tZiR6h2EA+VDdufYHfeaznprgga8tUF9Soiri2dl 3g== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2xf74s3xdb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 Jan 2020 06:59:29 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00E6xJo4074324; Tue, 14 Jan 2020 06:59:29 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3020.oracle.com with ESMTP id 2xh8ergxrn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 Jan 2020 06:59:28 +0000 Received: from abhmp0006.oracle.com (abhmp0006.oracle.com [141.146.116.12]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 00E6x2HU012071; Tue, 14 Jan 2020 06:59:02 GMT Received: from kadam (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 13 Jan 2020 22:59:01 -0800 Date: Tue, 14 Jan 2020 09:58:54 +0300 From: Dan Carpenter To: syzbot Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: kernel BUG at fs/namei.c:LINE! Message-ID: <20200114065854.GA3719@kadam> References: <00000000000008132d059c13c47b@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00000000000008132d059c13c47b@google.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9499 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=742 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001140060 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9499 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=803 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001140060 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 13, 2020 at 10:33:10PM -0800, syzbot wrote: > ------------[ cut here ]------------ > kernel BUG at fs/namei.c:684! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 9764 Comm: syz-executor.0 Not tainted > 5.5.0-rc5-next-20200113-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:unlazy_walk+0x306/0x3b0 fs/namei.c:684 > path_mountpoint.isra.0+0x1d5/0x340 fs/namei.c:2788 > filename_mountpoint+0x181/0x380 fs/namei.c:2809 > user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2839 > ksys_umount+0x164/0xef0 fs/namespace.c:1683 2289 static const char *path_init(struct nameidata *nd, unsigned flags) 2290 { 2291 int error; 2292 const char *s = nd->name->name; 2293 2294 if (!*s) 2295 flags &= ~LOOKUP_RCU; ^^^^^^^^^^^^^^^^^^^^ My guess is that LOOKUP_RCU gets cleared out here. Maybe the problem was introduced in commit e56b43b971a7 ("reimplement path_mountpoint() with less magic") because before we checked LOOKUP_RCU before calling unlazy_walk(). - /* If we're in rcuwalk, drop out of it to handle last component */ - if (nd->flags & LOOKUP_RCU) { - if (unlazy_walk(nd)) 2296 if (flags & LOOKUP_RCU) 2297 rcu_read_lock(); 2298 regards, dan carpenter