From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752076AbdIIWp1 (ORCPT ); Sat, 9 Sep 2017 18:45:27 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41445 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751857AbdIIWYn (ORCPT ); Sat, 9 Sep 2017 18:24:43 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" , "Mark Brown" Date: Sat, 09 Sep 2017 22:47:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 048/106] ASoC: Fix use-after-free at card unregistration In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.93-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 4efda5f2130da033aeedc5b3205569893b910de2 upstream. 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 Signed-off-by: Takashi Iwai Signed-off-by: Mark Brown [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- sound/soc/soc-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -1574,6 +1574,9 @@ static int soc_cleanup_card_resources(st flush_delayed_work_sync(&rtd->delayed_work); } + /* free the ALSA card at first; this syncs with pending operations */ + snd_card_free(card->snd_card); + /* remove auxiliary devices */ for (i = 0; i < card->num_aux_devs; i++) soc_remove_aux_dev(card, i); @@ -1590,9 +1593,7 @@ static int soc_cleanup_card_resources(st snd_soc_dapm_free(&card->dapm); kfree(card->rtd); - snd_card_free(card->snd_card); return 0; - } /* removes a socdev */