From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH v2 12/12] ASoC: Fix use-after-free at card unregistration Date: Mon, 19 Jun 2017 11:25:13 +0200 Message-ID: References: <1497857229-12049-1-git-send-email-robert.jarzmik@free.fr> <1497857229-12049-13-git-send-email-robert.jarzmik@free.fr> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <1497857229-12049-13-git-send-email-robert.jarzmik@free.fr> Sender: stable-owner@vger.kernel.org To: Robert Jarzmik Cc: Dmitry Torokhov , Haojian Zhuang , Liam Girdwood , Mark Brown , Lee Jones , Lars-Peter Clausen , Charles Keepax , Jaroslav Kysela , Daniel Mack , alsa-devel@alsa-project.org, linux-arm-kernel@lists.infradead.org, patches@opensource.wolfsonmicro.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org List-Id: linux-input@vger.kernel.org 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 > >