FAILED: patch "[PATCH] ALSA: scarlett2: Fix buffer overflow in config retrieval" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 6f5c69f72e50d51be3a8c028ae7eda42c82902cb
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026012703-wrecking-unpicked-b43c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6f5c69f72e50d51be3a8c028ae7eda42c82902cb Mon Sep 17 00:00:00 2001
From: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
Date: Fri, 16 Jan 2026 17:27:06 -0800
Subject: [PATCH] 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 f2446bf3982c..bef8c9e544dd 100644
--- 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);