ALSA: scarlett2: Fix buffer overflow in config retrieval

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>

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index f2446bf3982c66a80a6ef0446fa606447ac32768..bef8c9e544dd3d352bf2ce7211ec29de99cf5692 100644 (file)
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -2533,13 +2533,13 @@ 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 (size == 4) {
-                       u32 *buf_32 = buf;
+               } 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);