Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755482AbdLOJqX (ORCPT ); Fri, 15 Dec 2017 04:46:23 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33718 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755123AbdLOJqQ (ORCPT ); Fri, 15 Dec 2017 04:46:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Robb Glasser , Nick Desaulniers , Takashi Iwai Subject: [PATCH 4.4 018/105] ALSA: pcm: prevent UAF in snd_pcm_info Date: Fri, 15 Dec 2017 10:44:16 +0100 Message-Id: <20171215092306.849959285@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171215092305.994559179@linuxfoundation.org> References: <20171215092305.994559179@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: 1115 Lines: 37 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Robb Glasser commit 362bca57f5d78220f8b5907b875961af9436e229 upstream. When the device descriptor is closed, the `substream->runtime` pointer is freed. But another thread may be in the ioctl handler, case SNDRV_CTL_IOCTL_PCM_INFO. This case calls snd_pcm_info_user() which calls snd_pcm_info() which accesses the now freed `substream->runtime`. Note: this fixes CVE-2017-0861 Signed-off-by: Robb Glasser Signed-off-by: Nick Desaulniers Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+) --- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -149,7 +149,9 @@ static int snd_pcm_control_ioctl(struct err = -ENXIO; goto _error; } + mutex_lock(&pcm->open_mutex); err = snd_pcm_info_user(substream, info); + mutex_unlock(&pcm->open_mutex); _error: mutex_unlock(®ister_mutex); return err;