[PATCH AUTOSEL 4.20 03/77] ALSA: compress: prevent potential divide by zero bugs

Sasha Levin
2019-02-15T02:43:18Z

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

[ Upstream commit 678e2b44c8e3fec3afc7202f1996a4500a50be93 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 26b5e245b074..8b78ddffa509 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -529,7 +529,8 @@ 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 */
--
2.19.1