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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 C3513C2D0A8 for ; Mon, 28 Sep 2020 16:13:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7972020809 for ; Mon, 28 Sep 2020 16:13:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="PXCpzIO2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="i1MLe1zt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726672AbgI1QNp (ORCPT ); Mon, 28 Sep 2020 12:13:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726281AbgI1QNp (ORCPT ); Mon, 28 Sep 2020 12:13:45 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9B71C061755; Mon, 28 Sep 2020 09:13:44 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1601309622; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fgursmpxb2O5tZTENK3QKNcBPtJOFO4D16e2e18XLWI=; b=PXCpzIO2y+d7baDTO2lerLR1Zg5n8DxenaTvnh3W+iij2F3wPnCcmIfnNnCG44pXW4YJ1t Hc+zBZ6W3bv4XgZ5QZjVa7SYP4Fo82SkQHl9UYU0aglc3Lw7cEBNS+K1qvkF5lv8k7PjNm o+bXKxBWIfxA85bDmcbeHzNX0645TaH0dc+Blxoy0WOwCba+TjpjezgU+qCZRBoo8Oc01M AGMtmBI2QH/PXHT5ewze9sTEe4/+T5ULwWKjEiIPyTnryGOOQeSp0F23hzfNYPwy7Dg1zm 1Vs+lk/xTxgL1PDJCcB0okhUr/6/70TR8zE8Mo7dwwUtM0hQkRK1rS7hG6/Xyg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1601309622; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fgursmpxb2O5tZTENK3QKNcBPtJOFO4D16e2e18XLWI=; b=i1MLe1ztX4w4kIdRrY03/b5cyV5KiZ/2UZ+FERHut/eIc7Bq/k+HmqyxnNGkMDH4/s1WWr aRV6Ehox/Vqvl2Cw== To: syzbot , davem@davemloft.net, hchunhui@mail.ustc.edu.cn, hdanton@sina.com, ja@ssi.bg, jmorris@namei.org, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, yoshfuji@linux-ipv6.org, Johannes Berg Subject: Re: WARNING in hrtimer_forward In-Reply-To: <0000000000007d5ec805b04c5fc8@google.com> References: <0000000000007d5ec805b04c5fc8@google.com> Date: Mon, 28 Sep 2020 18:13:42 +0200 Message-ID: <87pn65khft.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 27 2020 at 07:29, syzbot wrote: > syzbot has bisected this issue to: > > commit 0e7bbcc104baaade4f64205e9706b7d43c46db7d > Author: Julian Anastasov > Date: Wed Jul 27 06:56:50 2016 +0000 > > neigh: allow admin to set NUD_STALE > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1661d187900000 > start commit: ba5f4cfe bpf: Add comment to document BTF type PTR_TO_BTF_.. > git tree: bpf-next > final oops: https://syzkaller.appspot.com/x/report.txt?x=1561d187900000 > console output: https://syzkaller.appspot.com/x/log.txt?x=1161d187900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d44e1360b76d34dc > dashboard link: https://syzkaller.appspot.com/bug?extid=ca740b95a16399ceb9a5 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1148fe4b900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f5218d900000 > > Reported-by: syzbot+ca740b95a16399ceb9a5@syzkaller.appspotmail.com > Fixes: 0e7bbcc104ba ("neigh: allow admin to set NUD_STALE") That bisect does not make any sense and reverting the commit on top of next does not help either. What happens is: fail-16132 [029] .... 933.714866: sys_enter: NR 16 (3, 8b28, 20000000, 0, 0, 0) -0 [001] d.s2 933.715768: hrtimer_cancel: hrtimer=00000000fe9fe1b9 -0 [001] ..s1 933.715771: hrtimer_expire_entry: hrtimer=00000000fe9fe1b9 function=mac80211_hwsim_beacon now=933716506319 fail-16132 [029] d..1 933.715794: hrtimer_start: hrtimer=00000000fe9fe1b9 function=mac80211_hwsim_beacon expires=933818720770 softexpires=933818720770 mode=REL|SOFT -0 [001] ..s1 933.715812: hrtimer_forward: hrtimer=00000000fe9fe1b9 So the timer was armed at some point and then the expiry which does the forward races with the ioctl which starts the timer. Lack of serialization or such ... Thanks, tglx