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Message-Id: <20160304153002.159016244@1wt.eu>
Date: Fri, 04 Mar 2016 16:30:33 +0100
From: Willy Tarreau <w@....eu>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Nicolas Boichat <drinkcat@...omium.org>,
Takashi Iwai <tiwai@...e.de>,
Ben Hutchings <ben@...adent.org.uk>, Willy Tarreau <w@....eu>
Subject: [PATCH 2.6.32 33/55] ALSA: pcm: Fix snd_pcm_hw_params struct copy in compat
mode
2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
From: Nicolas Boichat <drinkcat@...omium.org>
commit 43c54b8c7cfe22f868a751ba8a59abf1724160b1 upstream.
This reverts one hunk of
commit ef44a1ec6eee ("ALSA: sound/core: use memdup_user()"), which
replaced a number of kmalloc followed by memcpy with memdup calls.
In this case, we are copying from a struct snd_pcm_hw_params32 to
a struct snd_pcm_hw_params, but the latter is 4 bytes longer than
the 32-bit version, so we need to separate kmalloc and copy calls.
This actually leads to an out-of-bounds memory access later on
in sound/soc/soc-pcm.c:soc_pcm_hw_params() (detected using KASan).
Fixes: ef44a1ec6eee ('ALSA: sound/core: use memdup_user()')
Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Willy Tarreau <w@....eu>
---
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 038232d..0423434 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -232,10 +232,15 @@ 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);
--
1.7.12.2.21.g234cd45.dirty
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