[PATCH 6.1.y] ALSA: scarlett2: Fix buffer overflow in config retrieval

[Sasha Levin <sashal@kernel.org>]

From: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>

[ Upstream commit 6f5c69f72e50d51be3a8c028ae7eda42c82902cb ]

The scarlett2_usb_get_config() function has a logic error in the
endianness conversion code that can cause buffer overflows when
count > 1.

The code checks `if (size == 2)` where `size` is the total buffer size in
bytes, then loops `count` times treating each element as u16 (2 bytes).
This causes the loop to access `count * 2` bytes when the buffer only
has `size` bytes allocated.

Fix by checking the element size (config_item->size) instead of the
total buffer size. This ensures the endianness conversion matches the
actual element type.

Fixes: ac34df733d2d ("ALSA: usb-audio: scarlett2: Update get_config to do endian conversion")
Cc: stable@vger.kernel.org
Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
Link: https://patch.msgid.link/20260117012706.1715574-1-samasth.norway.ananda@oracle.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[ add 32-bit handling block ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/mixer_scarlett2.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index fa2bfa102ab56..ddb8f8d625841 100644
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -1408,11 +1408,16 @@ static int scarlett2_usb_get_config(
 		err = scarlett2_usb_get(mixer, config_item->offset, buf, size);
 		if (err < 0)
 			return err;
-		if (size == 2) {
+		if (config_item->size == 16) {
 			u16 *buf_16 = buf;
 
 			for (i = 0; i < count; i++, buf_16++)
 				*buf_16 = le16_to_cpu(*(__le16 *)buf_16);
+		} else if (config_item->size == 32) {
+			u32 *buf_32 = (u32 *)buf;
+
+			for (i = 0; i < count; i++, buf_32++)
+				*buf_32 = le32_to_cpu(*(__le32 *)buf_32);
 		}
 		return 0;
 	}
-- 
2.51.0