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 5B250C433EF for ; Sat, 11 Dec 2021 10:05:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230283AbhLKKFw (ORCPT ); Sat, 11 Dec 2021 05:05:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229841AbhLKKFu (ORCPT ); Sat, 11 Dec 2021 05:05:50 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8238CC061714 for ; Sat, 11 Dec 2021 02:05:50 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 1F021CE2F50 for ; Sat, 11 Dec 2021 10:05:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B6EBC341C7; Sat, 11 Dec 2021 10:05:43 +0000 (UTC) Date: Sat, 11 Dec 2021 11:05:40 +0100 From: Christian Brauner To: syzbot Cc: akpm@linux-foundation.org, cxfcosmos@gmail.com, ebiederm@xmission.com, glider@google.com, legion@kernel.org, linux-kernel@vger.kernel.org, serge@hallyn.com, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] KMSAN: uninit-value in make_kuid Message-ID: <20211211100540.qe5jzvbxnbi2mzfx@wittgenstein> References: <000000000000f1de5405d2ca4ae2@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <000000000000f1de5405d2ca4ae2@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 10, 2021 at 04:59:26AM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: b0f85c4ccdd4 kmsan: report: add dump_stack_print_info() > git tree: https://github.com/google/kmsan.git master > console output: https://syzkaller.appspot.com/x/log.txt?x=1704eaf9b00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=e00a8959fdd3f3e8 > dashboard link: https://syzkaller.appspot.com/bug?extid=ce39644883793043ee77 > compiler: clang version 14.0.0 (git@github.com:llvm/llvm-project.git 0996585c8e3b3d409494eb5f1cad714b9e1f7fb5), GNU ld (GNU Binutils for Debian) 2.35.2 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+ce39644883793043ee77@syzkaller.appspotmail.com I think this is triggered by the same 9p bug where it copies uninitialized memory during setattr and then proceeds to send that uninitialized memory over the wire. A patch for this was sent to 9p devel but it seems to not have made it into mainline or -next just yet: https://sourceforge.net/p/v9fs/mailman/message/37392685/