From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751496AbcIBNNt (ORCPT <rfc822;w@1wt.eu>);
        Fri, 2 Sep 2016 09:13:49 -0400
Received: from mx2.suse.de ([195.135.220.15]:32913 "EHLO mx2.suse.de"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1750859AbcIBNNr (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 2 Sep 2016 09:13:47 -0400
Date: Fri, 02 Sep 2016 15:13:45 +0200
Message-ID: <s5hzinqe96e.wl-tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Jaroslav Kysela <perex@perex.cz>, alsa-devel@alsa-project.org,
        syzkaller <syzkaller@googlegroups.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] ALSA: timer: fix NULL pointer dereference in read()/ioctl() race
In-Reply-To: <14739ff0-b415-08e5-5f5c-a29a99fe473e@oracle.com>
References: <20160828223351.32489-1-vegard.nossum@oracle.com>
        <s5hr39883ch.wl-tiwai@suse.de>
        <0560accf-2461-8205-6377-32b464bfce7e@oracle.com>
        <14739ff0-b415-08e5-5f5c-a29a99fe473e@oracle.com>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka)
 FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.5
 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka")
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 02 Sep 2016 14:34:47 +0200,
Vegard Nossum wrote:
> 
> On 08/29/2016 09:14 AM, Vegard Nossum wrote:
> > On 08/29/2016 09:02 AM, Takashi Iwai wrote:
> >> On Mon, 29 Aug 2016 00:33:49 +0200,
> >> Vegard Nossum wrote:
> >>> @@ -1602,15 +1602,25 @@ static int snd_timer_user_tselect(struct file
> >>> *file,
> >>>      kfree(tu->tqueue);
> >>>      tu->tqueue = NULL;
> >>>      if (tu->tread) {
> >>> -        tu->tqueue = kmalloc(tu->queue_size * sizeof(struct
> >>> snd_timer_tread),
> >>> +        struct snd_timer_tread *ttr;
> >>> +        ttr = kmalloc(tu->queue_size * sizeof(struct snd_timer_tread),
> >>>                       GFP_KERNEL);
> >>> -        if (tu->tqueue == NULL)
> >>> +        if (ttr) {
> >>> +            kfree(tu->tqueue);
> >>> +            tu->tqueue = ttr;
> >>
> >> This looks like the double-tree, as you didn't remove the kfree() call
> >> in the above.  But, I guess this change is superfluous when you
> >> introduce the mutex at...
> >
> > You're right, this hunk is garbage.
> >
> > Please see the new patch (attached), I also changed the patch
> > description slightly to match the changes.
> >
> > I'll start running some tests on the new patch.
> 
> I tested the new patch (from the email I'm replying to). It seems to
> work for me.

OK, queued now.  Thanks!


Takashi