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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 3BA24C433E6 for ; Mon, 1 Feb 2021 12:51:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0736064E9E for ; Mon, 1 Feb 2021 12:51:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231657AbhBAMui (ORCPT ); Mon, 1 Feb 2021 07:50:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231636AbhBAMuO (ORCPT ); Mon, 1 Feb 2021 07:50:14 -0500 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DC65C0613D6; Mon, 1 Feb 2021 04:49:33 -0800 (PST) Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94) (envelope-from ) id 1l6Yds-00EQVZ-PU; Mon, 01 Feb 2021 13:49:20 +0100 Message-ID: <0a982b705b37e7bd3f47cd437b37d8f62dce15e4.camel@sipsolutions.net> Subject: Re: possible deadlock in cfg80211_netdev_notifier_call From: Johannes Berg To: Mike Rapoport , syzbot Cc: akpm@linux-foundation.org, davem@davemloft.net, hagen@jauu.net, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, sfr@canb.auug.org.au, syzkaller-bugs@googlegroups.com Date: Mon, 01 Feb 2021 13:49:18 +0100 In-Reply-To: <20210201123728.GF299309@linux.ibm.com> References: <000000000000c3a1b705ba42d1ca@google.com> <20210201123728.GF299309@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-malware-bazaar: not-scanned Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Mon, 2021-02-01 at 14:37 +0200, Mike Rapoport wrote: > On Mon, Feb 01, 2021 at 01:17:13AM -0800, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: b01f250d Add linux-next specific files for 20210129 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=14daa408d00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=725bc96dc234fda7 > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ae0ca9d7737ad1a62b7 > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1757f2a0d00000 > > > > The issue was bisected to: > > > > commit cc9327f3b085ba5be5639a5ec3ce5b08a0f14a7c > > Author: Mike Rapoport > > Date: Thu Jan 28 07:42:40 2021 +0000 > > > > mm: introduce memfd_secret system call to create "secret" memory areas > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1505d28cd00000 > > final oops: https://syzkaller.appspot.com/x/report.txt?x=1705d28cd00000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=1305d28cd00000 > > Sounds really weird to me. At this point the memfd_secret syscall is not > even wired to arch syscall handlers. I cannot see how it can be a reason of > deadlock in wireless... Yeah, forget about it. Usually this is a consequence of the way syzbot creates tests - it might have created something like if (!create_secret_memfd()) return; try_something_on_wireless() and then of course without your patch it cannot get to the wireless bits. Pretty sure I know what's going on here, I'll take a closer look later. johannes