linux-kernel - [PATCH] USB PCM Sound driver neglects kmalloc return value check and may deref NULL.

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Message-ID: <alpine.LNX.2.00.1010292032550.24561@swampdragon.chaosbits.net>
Date:	Fri, 29 Oct 2010 20:40:23 +0200 (CEST)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-kernel@...r.kernel.org
cc:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>
Subject: [PATCH] USB PCM Sound driver neglects kmalloc return value check
 and may deref NULL.

sound/usb/pcm.c::snd_usb_pcm_check_knot() fails to check the return value 
from kmalloc() and may end up dereferencing a null pointer.
The patch below (compile tested only) should take care of that little 
problem.

Signed-off-by: Jesper Juhl <jj@...osbits.net>
---
 pcm.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index cff3a3c..4132522 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -676,8 +676,10 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
 	if (!needs_knot)
 		return 0;

-	subs->rate_list.count = count;
 	subs->rate_list.list = kmalloc(sizeof(int) * count, GFP_KERNEL);
+	if (!subs->rate_list.list)
+		return -ENOMEM;
+	subs->rate_list.count = count;
 	subs->rate_list.mask = 0;
 	count = 0;
 	list_for_each_entry(fp, &subs->fmt_list, list) {

-- 
Jesper Juhl <jj@...osbits.net>             http://www.chaosbits.net/
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