Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753802AbdFSJZR (ORCPT ); Mon, 19 Jun 2017 05:25:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:50739 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750952AbdFSJZQ (ORCPT ); Mon, 19 Jun 2017 05:25:16 -0400 Date: Mon, 19 Jun 2017 11:25:13 +0200 Message-ID: From: Takashi Iwai To: "Robert Jarzmik" Cc: "Dmitry Torokhov" , "Haojian Zhuang" , "Liam Girdwood" , "Mark Brown" , "Lee Jones" , "Lars-Peter Clausen" , "Charles Keepax" , "Jaroslav Kysela" , "Daniel Mack" , , , , , , Subject: Re: [PATCH v2 12/12] ASoC: Fix use-after-free at card unregistration In-Reply-To: <1497857229-12049-13-git-send-email-robert.jarzmik@free.fr> References: <1497857229-12049-1-git-send-email-robert.jarzmik@free.fr> <1497857229-12049-13-git-send-email-robert.jarzmik@free.fr> 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/25.2 (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: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1743 Lines: 58 On Mon, 19 Jun 2017 09:27:09 +0200, Robert Jarzmik wrote: > > From: Takashi Iwai > > soc_cleanup_card_resources() call snd_card_free() at the last of its > procedure. This turned out to lead to a use-after-free. > PCM runtimes have been already removed via soc_remove_pcm_runtimes(), > while it's dereferenced later in soc_pcm_free() called via > snd_card_free(). > > The fix is simple: just move the snd_card_free() call to the beginning > of the whole procedure. This also gives another benefit: it > guarantees that all operations have been shut down before actually > releasing the resources, which was racy until now. > > Reported-and-tested-by: Robert Jarzmik > Cc: > Signed-off-by: Takashi Iwai This patch must be superfluous :) Takashi > --- > sound/soc/soc-core.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c > index 2722bb0c5573..98d60f471c5d 100644 > --- a/sound/soc/soc-core.c > +++ b/sound/soc/soc-core.c > @@ -2286,6 +2286,9 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) > list_for_each_entry(rtd, &card->rtd_list, list) > flush_delayed_work(&rtd->delayed_work); > > + /* free the ALSA card at first; this syncs with pending operations */ > + snd_card_free(card->snd_card); > + > /* remove and free each DAI */ > soc_remove_dai_links(card); > soc_remove_pcm_runtimes(card); > @@ -2300,9 +2303,7 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) > if (card->remove) > card->remove(card); > > - snd_card_free(card->snd_card); > return 0; > - > } > > /* removes a socdev */ > -- > 2.1.4 > >