# \[PATCH AUTOSEL 5.4 10/40\] staging: most: sound: add sanity check for function argument

- From: Sasha Levin \<sashal@kernel.org\>
- Date: 2021-02-24 13:43:42 
- List: stable
- Page: https://ratatoskr.run/stable/2021/02/6277804
- Thread: https://ratatoskr.run/stable/2021/02/6277792/t.md

```text
From: Christian Gromm <christian.gromm@microchip.com>

[ Upstream commit 45b754ae5b82949dca2b6e74fa680313cefdc813 ]

This patch checks the function parameter 'bytes' before doing the
subtraction to prevent memory corruption.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Reported-by: Dan Carpenter <redacted>
Link: https://lore.kernel.org/r/1612282865-21846-1-git-send-email-christian.gromm@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/staging/most/sound/sound.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/staging/most/sound/sound.c b/drivers/staging/most/sound/sound.c
index 79817061fcfa4..4225ee9fcf7bf 100644
--- a/drivers/staging/most/sound/sound.c
+++ b/drivers/staging/most/sound/sound.c
@@ -98,6 +98,8 @@ static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
 {
 	unsigned int i = 0;
 
+	if (bytes < 2)
+		return;
 	while (i < bytes - 2) {
 		dest[i] = source[i + 2];
 		dest[i + 1] = source[i + 1];
-- 
2.27.0

```