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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 F1890C43387 for ; Tue, 8 Jan 2019 13:50:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCB942087E for ; Tue, 8 Jan 2019 13:50:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546955424; bh=35yoXLMJlxhAzXFrmdpn9DDgAlLDniGkmEqLPnbN19c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=W4jXKVcuTUQ0I6vJx5hYh0T+OK4goZrEz6CidI1/LHgzOMCXxY/55c0v5u8+TK+pL FwtMbak3Ki8fNj6Trxoqb7pe3rHezEJtBk3/hoPlolxQ7MrpFNIMnTHT8VRLAF+mHf 9wkFFwqmzVr5F6iQo67rO42ZJGAim7LOs9XDRFcE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728495AbfAHNuX (ORCPT ); Tue, 8 Jan 2019 08:50:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:41684 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728212AbfAHNuX (ORCPT ); Tue, 8 Jan 2019 08:50:23 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 51BDC206BB; Tue, 8 Jan 2019 13:50:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546955422; bh=35yoXLMJlxhAzXFrmdpn9DDgAlLDniGkmEqLPnbN19c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wd66UOWHtuDEVFGJZGaOAWaLOywbwDe3GAdWc+GGHX/fdlnsYLJz0VdkWbPE5ET0f CGAKVu/KV34V8y+u2ol+hFn+EsIeocUVacTmKWAl/pAM+6E9AaFBgrHM8kRhZJJ9Ng bm1uPRFA25DMt60cLtRYDHP7cXp0Dyzvdt8wsYG4= Date: Tue, 8 Jan 2019 14:50:20 +0100 From: Greg KH To: Kyungtae Kim Cc: w.d.hubbs@gmail.com, chris@the-brannons.com, kirk@reisers.ca, samuel.thibault@ens-lyon.org, Byoungyoung Lee , DaeRyong Jeong , speakup@linux-speakup.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com Subject: Re: general protection fault in spk_ttyio_ldisc_close Message-ID: <20190108135020.GA10504@kroah.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 08, 2019 at 08:37:37AM -0500, Kyungtae Kim wrote: > We report a bug in linux-4.20: "general protection fault in > spk_ttyio_ldisc_close" > > kernel config: https://kt0755.github.io/etc/config_v4.20_stable > repro: https://kt0755.github.io/etc/repro.a670e.c > > This occurs when the function kfree is about to execute > (driver/staging/speakup/spk_ttyio.c:68). > Particularly, kfree takes the argument like speakup_tty->disc_data. > But speakup_tty is invalid, so the pointer dereference causes GPF. > At a glance, it seems that speakup_tty was deallocated somewhere ahead of kfree. How did you trigger this? Did you shut down and close the device already somehow? Do you have a real tty device that is driven by the device? thanks, greg k-h