Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753878AbdFSH3J (ORCPT ); Mon, 19 Jun 2017 03:29:09 -0400 Received: from smtp03.smtpout.orange.fr ([80.12.242.125]:20532 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753534AbdFSH3H (ORCPT ); Mon, 19 Jun 2017 03:29:07 -0400 X-ME-Helo: belgarion.home X-ME-Date: Mon, 19 Jun 2017 09:28:35 +0200 X-ME-IP: 109.220.219.63 From: Robert Jarzmik To: Dmitry Torokhov , Lee Jones , Jaroslav Kysela , Takashi Iwai , Daniel Mack , Haojian Zhuang , Robert Jarzmik , Liam Girdwood , Mark Brown , Lars-Peter Clausen , Charles Keepax Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, patches@opensource.wolfsonmicro.com, alsa-devel@alsa-project.org, linux-arm-kernel@lists.infradead.org, Takashi Iwai , Subject: [PATCH v2 12/12] ASoC: Fix use-after-free at card unregistration Date: Mon, 19 Jun 2017 09:27:09 +0200 Message-Id: <1497857229-12049-13-git-send-email-robert.jarzmik@free.fr> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1497857229-12049-1-git-send-email-robert.jarzmik@free.fr> References: <1497857229-12049-1-git-send-email-robert.jarzmik@free.fr> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1537 Lines: 46 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 --- 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