From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753551AbcARDts (ORCPT ); Sun, 17 Jan 2016 22:49:48 -0500 Received: from mail-pf0-f180.google.com ([209.85.192.180]:33428 "EHLO mail-pf0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752997AbcARDtp (ORCPT ); Sun, 17 Jan 2016 22:49:45 -0500 From: Nicolas Boichat To: Takashi Iwai Cc: Jaroslav Kysela , Nicolas Boichat , Pierre-Louis Bossart , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: [PATCH] ALSA: pcm: Fix snd_pcm_hw_params struct copy in compat mode Date: Mon, 18 Jan 2016 11:49:18 +0800 Message-Id: <1453088958-6214-1-git-send-email-drinkcat@chromium.org> X-Mailer: git-send-email 2.6.0.rc2.230.g3dd15c0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Running a kernel with KASan enabled, we spotted that the following read in sound/soc/soc-pcm.c:soc_pcm_hw_params() is out of bounds: /* copy params for each codec */ codec_params = *params; The problem comes from sound/core/pcm_compat.c, snd_pcm_ioctl_hw_params_compat, where we're copying from a struct snd_pcm_hw_params to a struct snd_pcm_hw_params32: /* only fifo_size is different, so just copy all */ data = memdup_user(data32, sizeof(*data32)); It turns out that snd_pcm_hw_params is 4 bytes longer than snd_pcm_hw_params32, that's why an out-of-bounds read happens. We separate kmalloc and memory copy operations to make sure data has the correct length. Signed-off-by: Nicolas Boichat --- sound/core/pcm_compat.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c index b48b434..9630e9f 100644 --- a/sound/core/pcm_compat.c +++ b/sound/core/pcm_compat.c @@ -255,10 +255,15 @@ static int snd_pcm_ioctl_hw_params_compat(struct snd_pcm_substream *substream, if (! (runtime = substream->runtime)) return -ENOTTY; - /* only fifo_size is different, so just copy all */ - data = memdup_user(data32, sizeof(*data32)); - if (IS_ERR(data)) - return PTR_ERR(data); + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + /* only fifo_size (RO from userspace) is different, so just copy all */ + if (copy_from_user(data, data32, sizeof(*data32))) { + err = -EFAULT; + goto error; + } if (refine) err = snd_pcm_hw_refine(substream, data); -- 2.6.0.rc2.230.g3dd15c0