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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 58425C43457 for ; Fri, 9 Oct 2020 04:05:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 184092224A for ; Fri, 9 Oct 2020 04:05:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gshiYZyB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726367AbgJIEFq (ORCPT ); Fri, 9 Oct 2020 00:05:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:35510 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725978AbgJIEFo (ORCPT ); Fri, 9 Oct 2020 00:05:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602216343; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0LJZLfN1evxEALdYZ+iKwkAO+jzveYCVlDmJws2G9/M=; b=gshiYZyB/VenNcMmQITYFdsQHpyK09ZlZvlZ0Y8oFLOHQrdQoKbw09oOBZonaMNqA7phY+ kBEQ2tb+O0ASjV0iUKdtfC1fdi4c5VldfGnKdoYoWEyVPW97pSC37mg3XVRNAB0SXY7Mra OWTguRg+7tG8tGFjNHHe8/mnQb8PA74= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-456-xglw9SF9NZWwo7f1JWlwBg-1; Fri, 09 Oct 2020 00:05:39 -0400 X-MC-Unique: xglw9SF9NZWwo7f1JWlwBg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 299D457083; Fri, 9 Oct 2020 04:05:37 +0000 (UTC) Received: from T590 (ovpn-13-88.pek2.redhat.com [10.72.13.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 851FC10013C1; Fri, 9 Oct 2020 04:05:29 +0000 (UTC) Date: Fri, 9 Oct 2020 12:05:25 +0800 From: Ming Lei To: Jens Axboe Cc: syzbot , bcrl@kvack.org, hch@lst.de, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tj@kernel.org, viro@zeniv.linux.org.uk, vkabatov@redhat.com Subject: Re: general protection fault in percpu_ref_exit Message-ID: <20201009040525.GB27356@T590> References: <000000000000b1412b05b12eab0a@google.com> <165db20c-bfc5-fca8-1ecf-45d85ea5d9e2@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <165db20c-bfc5-fca8-1ecf-45d85ea5d9e2@kernel.dk> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 08, 2020 at 07:23:02PM -0600, Jens Axboe wrote: > On 10/8/20 2:28 PM, syzbot wrote: > > syzbot has bisected this issue to: > > > > commit 2b0d3d3e4fcfb19d10f9a82910b8f0f05c56ee3e > > Author: Ming Lei > > Date: Thu Oct 1 15:48:41 2020 +0000 > > > > percpu_ref: reduce memory footprint of percpu_ref in fast path > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=126930d0500000 > > start commit: 8b787da7 Add linux-next specific files for 20201007 > > git tree: linux-next > > final oops: https://syzkaller.appspot.com/x/report.txt?x=116930d0500000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=166930d0500000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=aac055e9c8fbd2b8 > > dashboard link: https://syzkaller.appspot.com/bug?extid=fd15ff734dace9e16437 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119a0568500000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=106c0a8b900000 > > > > Reported-by: syzbot+fd15ff734dace9e16437@syzkaller.appspotmail.com > > Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") > > > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > Ming, this looks like a call of percpu_ref_exit() on a zeroed refs (that > hasn't been initialized). Really a caller error imho, but might make sense > to be a bit safer there. Hello Jens, The fix is sent out as: https://lore.kernel.org/linux-block/20201009040356.43802-1-ming.lei@redhat.com/T/#u Sorry for making the trouble. Thanks, Ming