Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754769AbdFLPg5 (ORCPT ); Mon, 12 Jun 2017 11:36:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41684 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754194AbdFLPgy (ORCPT ); Mon, 12 Jun 2017 11:36:54 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai , Mark Brown Subject: [PATCH 4.9 104/119] ASoC: Fix use-after-free at card unregistration Date: Mon, 12 Jun 2017 17:26:06 +0200 Message-Id: <20170612152603.951891769@linuxfoundation.org> X-Mailer: git-send-email 2.13.1 In-Reply-To: <20170612152556.601664278@linuxfoundation.org> References: <20170612152556.601664278@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1624 Lines: 51 4.9-stable 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 Signed-off-by: Greg Kroah-Hartman --- 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 @@ -2076,6 +2076,9 @@ static int soc_cleanup_card_resources(st 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); @@ -2090,9 +2093,7 @@ static int soc_cleanup_card_resources(st if (card->remove) card->remove(card); - snd_card_free(card->snd_card); return 0; - } /* removes a socdev */