linux-kernel - [PATCH 3.16 273/305] ALSA: compress: fix an integer overflow check

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Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Dan Carpenter" <dan.carpenter@...cle.com>,
	"Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.16 273/305] ALSA: compress: fix an integer overflow check

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 6217e5ede23285ddfee10d2e4ba0cc2d4c046205 upstream.

I previously added an integer overflow check here but looking at it now,
it's still buggy.

The bug happens in snd_compr_allocate_buffer().  We multiply
".fragments" and ".fragment_size" and that doesn't overflow but then we
save it in an unsigned int so it truncates the high bits away and we
allocate a smaller than expected size.

Fixes: b35cc8225845 ('ALSA: compress_core: integer overflow in snd_compr_allocate_buffer()')
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/core/compress_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -500,7 +500,7 @@ static int snd_compress_check_input(stru
 {
 	/* first let's check the buffer parameter's */
 	if (params->buffer.fragment_size == 0 ||
-			params->buffer.fragments > SIZE_MAX / params->buffer.fragment_size)
+	    params->buffer.fragments > INT_MAX / params->buffer.fragment_size)
 		return -EINVAL;
 
 	/* now codec parameters */