FAILED: patch "[PATCH] ALSA: scarlett2: Allow flash writes ending at segment" failed to apply to 6.12-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x a69b677e47a80319ce148d61cc29a2b57006e78d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026052816-limelight-debtor-c8aa@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From a69b677e47a80319ce148d61cc29a2b57006e78d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A1ssio=20Gabriel?= <cassiogabrielcontato@gmail.com>
Date: Tue, 19 May 2026 11:46:19 -0300
Subject: [PATCH] ALSA: scarlett2: Allow flash writes ending at segment
 boundary
MIME-Version: 1.0
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scarlett2_hwdep_write() rejects writes when offset + count is greater than
or equal to the selected flash segment size. That incorrectly treats a
write ending exactly at the end of the segment as out of space, although
the last byte written is still within the segment.

Split invalid argument checks from the segment-space check, keep
zero-length writes as no-ops, and compare count against the remaining
segment size. This permits exact-end writes and avoids relying on
offset + count before deciding whether the request is in bounds.

Fixes: 1abfbd3c9527 ("ALSA: scarlett2: Add support for uploading new firmware")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260519-alsa-scarlett2-flash-write-boundary-v1-1-b550480e92da@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index 0f83f8981213..8e80a7165faf 100644
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -9187,12 +9187,15 @@ static long scarlett2_hwdep_write(struct snd_hwdep *hw,
 	flash_size = private->flash_segment_blocks[segment_id] *
 		     SCARLETT2_FLASH_BLOCK_SIZE;
 
-	if (count < 0 || *offset < 0 || *offset + count >= flash_size)
-		return -ENOSPC;
+	if (count < 0 || *offset < 0)
+		return -EINVAL;
 
 	if (!count)
 		return 0;
 
+	if (*offset >= flash_size || count > flash_size - *offset)
+		return -ENOSPC;
+
 	/* Limit the *req size to SCARLETT2_FLASH_RW_MAX */
 	if (count > max_data_size)
 		count = max_data_size;