[alsa-devel] [patch] ALSA: compress: info leak in snd_compr_get_caps()

Takashi Iwai tiwai at suse.de
Mon Apr 22 10:42:25 CEST 2013

At Sun, 21 Apr 2013 14:07:29 +0300,
Dan Carpenter wrote:
> If the ->get_caps() function doesn't clear the buffer then there would
> stack information leaked to userspace.  For example,
> soc_compr_get_caps() can return success without clearing the buffer.

Thanks, applied now.

I found that we have also a similar problem in other ioctls
(snd_compr_get_codec_caps() and snd_compr_get_params()), so applied
the following patch in addition.


From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] ALSA: compress: Use kzalloc() for ioctls writing back data

Like the previous patch by Dan, we should clear the data to be
returned from certain compress ioctls, namely,
snd_compr_get_codec_caps() and snd_compr_get_params().
This time, we can simply replace kmalloc() with kzalloc().

Signed-off-by: Takashi Iwai <tiwai at suse.de>
 sound/core/compress_offload.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 664c693..a0bc47f 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -428,7 +428,7 @@ snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg)
 	if (!stream->ops->get_codec_caps)
 		return -ENXIO;
-	caps = kmalloc(sizeof(*caps), GFP_KERNEL);
+	caps = kzalloc(sizeof(*caps), GFP_KERNEL);
 	if (!caps)
 		return -ENOMEM;
@@ -545,7 +545,7 @@ snd_compr_get_params(struct snd_compr_stream *stream, unsigned long arg)
 	if (!stream->ops->get_params)
 		return -EBADFD;
-	params = kmalloc(sizeof(*params), GFP_KERNEL);
+	params = kzalloc(sizeof(*params), GFP_KERNEL);
 	if (!params)
 		return -ENOMEM;
 	retval = stream->ops->get_params(stream, params);

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