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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCDD1EE4980 for ; Fri, 18 Aug 2023 17:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379170AbjHRRnl (ORCPT ); Fri, 18 Aug 2023 13:43:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379229AbjHRRnZ (ORCPT ); Fri, 18 Aug 2023 13:43:25 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2B472102; Fri, 18 Aug 2023 10:43:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=emG3qXIaO7YAlWV3oGlGfhgkQo9laxPdQNiw90Gx9Wc=; b=fRiKkJZrSVPeWrWwrRPnd/vSim 4Vn0YBHUdC6Sd+z6WPjGYyiwUV8CXUKNkei8B6+n3dOkBEer3jYkMBCEbIBtNywosja1Fw0nQNeXT MvwgJmgcgkK4OJDITE5DE8pkZU4H4ayjcNdF6MWsYCI1lwLtyxW04c4TlzevCyfknnHoATTFu5xuk li6tPDD/kgEPC4isq0P+gJi1TL0Q9BI4l5iz3lVo8Un9b0EOUchCXL0U1WUv5Gf7LteKDYLlVATBu 8dqASGdTDwwe+xjiC7WZ3OaJzpcaBmQDu7AWMILuDqculAeLxge/xjEmR2tqttKyIdCdgb8D5vaVl slLjPsUQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qX3V9-00An9w-Sj; Fri, 18 Aug 2023 17:43:11 +0000 Date: Fri, 18 Aug 2023 18:43:11 +0100 From: Matthew Wilcox To: Kees Cook Cc: "Eric W. Biederman" , syzbot , anton@tuxera.com, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-ntfs-dev@lists.sourceforge.net, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: [syzbot] [ntfs?] WARNING in do_open_execat Message-ID: References: <000000000000c74d44060334d476@google.com> <87o7j471v8.fsf@email.froward.int.ebiederm.org> <202308181030.0DA3FD14@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202308181030.0DA3FD14@keescook> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 18, 2023 at 10:33:26AM -0700, Kees Cook wrote: > On Fri, Aug 18, 2023 at 11:26:51AM -0500, Eric W. Biederman wrote: > > syzbot writes: > > > > > Hello, > > > > > > syzbot found the following issue on: > > > > Not an issue. > > Nothing to do with ntfs. > > > > The code is working as designed and intended. > > > > syzbot generated a malformed exec and the kernel made it > > well formed and warned about it. > > > > Human beings who run syzbot please mark this as not an issue in your > > system. The directions don't have a way to say that the code is working > > as expected and designed. > > WARN and BUG should not be reachable from userspace, so if this can be > tripped we should take a closer look and likely fix it... > > > > HEAD commit: 16931859a650 Merge tag 'nfsd-6.5-4' of git://git.kernel.or.. > > > git tree: upstream > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=13e2673da80000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=aa796b6080b04102 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=6ec38f7a8db3b3fb1002 > > > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17cdbc65a80000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1262d8cfa80000 > > > > > > Downloadable assets: > > > disk image: https://storage.googleapis.com/syzbot-assets/eecc010800b4/disk-16931859.raw.xz > > > vmlinux: https://storage.googleapis.com/syzbot-assets/f45ae06377a7/vmlinux-16931859.xz > > > kernel image: https://storage.googleapis.com/syzbot-assets/68891896edba/bzImage-16931859.xz > > > mounted in repro: https://storage.googleapis.com/syzbot-assets/4b6ab78b223a/mount_0.gz > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+6ec38f7a8db3b3fb1002@syzkaller.appspotmail.com > > > > > > ntfs: volume version 3.1. > > > process 'syz-executor300' launched './file1' with NULL argv: empty string added > > > ------------[ cut here ]------------ > > > WARNING: CPU: 0 PID: 5020 at fs/exec.c:933 do_open_execat+0x18f/0x3f0 fs/exec.c:933 > > This is a double-check I left in place, since it shouldn't have been reachable: > > /* > * may_open() has already checked for this, so it should be > * impossible to trip now. But we need to be extra cautious > * and check again at the very end too. > */ > err = -EACCES; > if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || > path_noexec(&file->f_path))) > goto exit; > > So yes, let's figure this out... When trying to figure it out, remember that ntfs corrupts random memory, so all reports from syzbot that have "ntfs" in them should be discarded. I tried to tell them that all this work they're doing testing ntfs3 is pointless, but they won't listen.