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=-5.8 required=3.0 tests=BAYES_00,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 A5007C433E6 for ; Mon, 18 Jan 2021 09:47:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F9AD22B3F for ; Mon, 18 Jan 2021 09:47:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388681AbhARJlX (ORCPT ); Mon, 18 Jan 2021 04:41:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388673AbhARJac (ORCPT ); Mon, 18 Jan 2021 04:30:32 -0500 Received: from mail-wr1-x42f.google.com (mail-wr1-x42f.google.com [IPv6:2a00:1450:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6194AC0613C1 for ; Mon, 18 Jan 2021 01:29:38 -0800 (PST) Received: by mail-wr1-x42f.google.com with SMTP id 6so8426036wri.3 for ; Mon, 18 Jan 2021 01:29:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=CTgLJUEqtetOUnV2zas5KqZ4EY9oOOP8M49JHcOPywA=; b=I+4oFB0MgkgBjVm5Jj+c26yE7J3Obn5Uivn2n9Fp/Criu/5WvR9jSF+6l5Mftrkyl0 LywxDJBSpWgUWo+Waeuq7vjxe7019LkJvKBZ9uv52xIojUEC5UNPNBiDsYwwfcZqtttt tPWp9hSxYCsHc8M4d3gCPY9KSWXKYYLIS378E= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=CTgLJUEqtetOUnV2zas5KqZ4EY9oOOP8M49JHcOPywA=; b=RsBhvLm0PTVMqJherUnsELciA1J7T5ZHBkljsYI332kcDSC3IRTC+DwGkvo+5N1Xay CwaXZ5mfePwLMqm8ZT8wcDce518ZnjbJPYevUKBJzVaY4mqStVGv9vjgLa3O/EfS7ZRI 3yA/x5LA/nNbYb4eUXKz32u+5679azRNBq8dWoVGM8EVjBFlcvM3th1XJeQ3cBmS6C/L 7jJ9lHb6fUob03CW8deTXit1X//akJnwtCAtP9wV67fHG3u5vYZ3FoFDBnAQeCS4DRRw LJ9FW9mmCmKzXb9uyuG8ndMi/83gFeWR3t1D67/Dw2Ck03QMPi1Ae5A8FGZ4GQ87FE0B NN7Q== X-Gm-Message-State: AOAM530xtKTL69XjO+aj77f72iLeTPVtPJN/RE3OEwAzQ5xuMz2N5qkL 0Px+tWPSOGXGFHuLRrPkKWkM6OJGCEzOf3nH X-Google-Smtp-Source: ABdhPJwZD2NhTSuMUUe1JnXazKkGPQJ8zIJYw38ZA8GsmaChXIwZBv1OUFyczb0noJoTAULMPt4RQQ== X-Received: by 2002:adf:dd09:: with SMTP id a9mr24721347wrm.90.1610962176960; Mon, 18 Jan 2021 01:29:36 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id d7sm17087960wmb.47.2021.01.18.01.29.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Jan 2021 01:29:36 -0800 (PST) Date: Mon, 18 Jan 2021 10:29:34 +0100 From: Daniel Vetter To: syzbot Cc: b.zolnierkie@samsung.com, daniel.vetter@ffwll.ch, daniel.vetter@intel.com, dri-devel@lists.freedesktop.org, george.kennedy@oracle.com, gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, melissa.srw@gmail.com, natechancellor@gmail.com, sam@ravnborg.org, syzkaller-bugs@googlegroups.com, tzimmermann@suse.de, yepeilin.cs@gmail.com Subject: Re: BUG: unable to handle kernel NULL pointer dereference in fbcon_cursor Message-ID: Mail-Followup-To: syzbot , b.zolnierkie@samsung.com, daniel.vetter@intel.com, dri-devel@lists.freedesktop.org, george.kennedy@oracle.com, gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, melissa.srw@gmail.com, natechancellor@gmail.com, sam@ravnborg.org, syzkaller-bugs@googlegroups.com, tzimmermann@suse.de, yepeilin.cs@gmail.com References: <00000000000091111005b435456e@google.com> <000000000000c37b3a05b916e95a@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000000000000c37b3a05b916e95a@google.com> X-Operating-System: Linux phenom 5.7.0-1-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 17, 2021 at 03:29:05AM -0800, syzbot wrote: > syzbot has bisected this issue to: > > commit ea40d7857d5250e5400f38c69ef9e17321e9c4a2 > Author: Daniel Vetter > Date: Fri Oct 9 23:21:56 2020 +0000 > > drm/vkms: fbdev emulation support Not sure you want to annotate this, but this just makes the bug reproducible on vkms. It's a preexisting issue (probably a few decades old) of the fbcon code afaict. It might also be that you can only repro this when you have multiple fbcon drivers (vkms plus whatever your virtual machine has I guess). -Daniel > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=148e2748d00000 > start commit: b3a3cbde Add linux-next specific files for 20210115 > git tree: linux-next > final oops: https://syzkaller.appspot.com/x/report.txt?x=168e2748d00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=128e2748d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6ea08dae6aab586f > dashboard link: https://syzkaller.appspot.com/bug?extid=b67aaae8d3a927f68d20 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15cd8fe0d00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17af5258d00000 > > Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com > Fixes: ea40d7857d52 ("drm/vkms: fbdev emulation support") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch