[alsa-devel] [patch] ALSA: compress: fix an integer overflow check

[Dan Carpenter]

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 at oracle.com>
---
The other option would be to declare buffer_size as size_t instead of
an unsigned int.  This feels like a safer fix though.

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 7403f34..89028fa 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -491,7 +491,7 @@ 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 > SIZE_MAX / params->buffer.fragment_size)
+	    params->buffer.fragments > INT_MAX / params->buffer.fragment_size)
 		return -EINVAL;
 
 	/* now codec parameters */