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 16F46C433E9 for ; Mon, 18 Jan 2021 20:09:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEFE822D6F for ; Mon, 18 Jan 2021 20:09:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388448AbhARKod (ORCPT ); Mon, 18 Jan 2021 05:44:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388674AbhARJac (ORCPT ); Mon, 18 Jan 2021 04:30:32 -0500 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67CC8C0613CF for ; Mon, 18 Jan 2021 01:29:38 -0800 (PST) Received: by mail-wr1-x431.google.com with SMTP id q18so15747191wrn.1 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=lrU8hnRSArV3gGiMSIC4w80HOy34SZ2b0eOP1CC/1oOUUfDbXF52AUPo5EmeNag3Dg KeTq+VlFJFufrKYwSVXIvtNUftP5HSmeTTmpEAMX1oBroKqSPq/kxe+yukzXXtRYg6lY wveDXk5QJwEDRSyghk1VJKA14J0KOD17p3ceLgy9c9MAYyDqwLTOhYpqsElu4xhjRC5T S07Bkb6sTCxo8a89Y+zI9Rs5/po16Kkx2YiW54wSwf4j/Oz+Xzc5YxhBl3EZnlmc+Y7L KVk5VTZ/STINKJeWHgx0Ds9HBJ5uF6XKv5CnYMquzEmuu3yaOfe1+iZBDgcNh/VzuV5+ uz5g== X-Gm-Message-State: AOAM532HMCeHchZzLVjNzPnH58BvpxOqzn/7mxN1IrtWL8DTxRoWnMmr H1VndruiiJah65wJIx5HMq3FRw== 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-fbdev@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