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 11B64C43387 for ; Tue, 8 Jan 2019 14:25:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD7BE2087E for ; Tue, 8 Jan 2019 14:25:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546957511; bh=tjcPeNgVCU6GAmPRjwh1mRQFI2zeGDmYUhfi2iC1CeY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zb1eYOSgpz2Wp/kG9jxQqtyveJX+HsDmOJAl7mNH4jX8iMd+zqd2i8RL57FWaE/qn 3Eil2EmYTfTn1h7T8DwROIkHQ+5bWxfrOYyfw15ZYzcHNw8X3lDZfsEi5SeGVi8MeG o1sbesC7YUXEDhc7ZweWTPqSmkTA60pSaeWZPYkQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728834AbfAHOZL (ORCPT ); Tue, 8 Jan 2019 09:25:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:58654 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727662AbfAHOZK (ORCPT ); Tue, 8 Jan 2019 09:25:10 -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 67E7220850; Tue, 8 Jan 2019 14:25:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546957509; bh=tjcPeNgVCU6GAmPRjwh1mRQFI2zeGDmYUhfi2iC1CeY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BDDdKmgYnW4SzO7l1uGANnyucTjV1XhDGGn6nc1o1qJDvEHyKTFRW+NoCd8UlbHS7 O7UYhjTRFYBDJ8i1jSO2dQ5jcpiyRHU4APTiNjAbvsiPBaUu2oDUhVHF01ZC4TMFC3 2/3LP4qqmI8w4m/FTnGN82kXeM1EYe9W5MWQpfFM= Date: Tue, 8 Jan 2019 15:25:07 +0100 From: Greg KH To: Kyungtae Kim Cc: devel@driverdev.osuosl.org, kirk@reisers.ca, speakup@linux-speakup.org, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com, Byoungyoung Lee , Samuel Thibault , DaeRyong Jeong , Christopher Brannon Subject: Re: general protection fault in spk_ttyio_ldisc_close Message-ID: <20190108142507.GA13938@kroah.com> References: <20190108135020.GA10504@kroah.com> 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 09:15:02AM -0500, Kyungtae Kim wrote: > On Tue, Jan 8, 2019 at 8:50 AM Greg KH wrote: > > > > 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 > > For this crash, we did without real speakup tty device. How did you bind a non-real speakup tty device to the driver? > I'm currently trying to figure out how this actually happens. That would be great to figure out :) thanks, greg k-h