From 678e2b44c8e3fec3afc7202f1996a4500a50be93 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 21 Dec 2018 12:06:58 +0300
Subject: [PATCH] ALSA: compress: prevent potential divide by zero bugs
Git-commit: 678e2b44c8e3fec3afc7202f1996a4500a50be93
Patch-mainline: v5.0-rc4
References: bsc#1051510

The problem is seen in the q6asm_dai_compr_set_params() function:

	ret = q6asm_map_memory_regions(dir, prtd->audio_client, prtd->phys,
				       (prtd->pcm_size / prtd->periods),
                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
				       prtd->periods);

In this code prtd->pcm_size is the buffer_size and prtd->periods comes
from params->buffer.fragments.  If we allow the number of fragments to
be zero then it results in a divide by zero bug.  One possible fix would
be to use prtd->pcm_count directly instead of using the division to
re-calculate it.  But I decided that it doesn't really make sense to
allow zero fragments.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 sound/core/compress_offload.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index a5b09e75e787..f7d2b373da0a 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -541,7 +541,8 @@ static int snd_compress_check_input(struct snd_compr_params *params)
 {
 	/* first let's check the buffer parameter's */
 	if (params->buffer.fragment_size == 0 ||
-	    params->buffer.fragments > INT_MAX / params->buffer.fragment_size)
+	    params->buffer.fragments > INT_MAX / params->buffer.fragment_size ||
+	    params->buffer.fragments == 0)
 		return -EINVAL;
 
 	/* now codec parameters */
-- 
2.16.4