FAILED: patch "[PATCH] Input: byd - synchronize timer deletion before freeing" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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 <[email protected]>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x c83e79c0842ed29860648bcce5022ef0ba5001c6
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026082045-around-contort-ce2c@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From c83e79c0842ed29860648bcce5022ef0ba5001c6 Mon Sep 17 00:00:00 2001
From: Linmao Li <[email protected]>
Date: Mon, 20 Jul 2026 14:12:59 +0800
Subject: [PATCH] Input: byd - synchronize timer deletion before freeing
private data

byd_disconnect() uses timer_delete() before freeing the driver's private data. This does not wait for a running byd_clear_touch() callback, which dereferences the private data and its psmouse pointer. A callback racing with disconnect can therefore access the private data after it has been freed. The timer can also still be re-armed by byd_process_byte() while the disconnect is in progress.

Use timer_shutdown_sync() before freeing the private data: it waits for a running callback and turns any later re-arm attempt into a no-op.

index f5770a3af2f1..5fc3c629590a 100644
@@ -423,7 +423,7 @@ static void byd_disconnect(struct psmouse *psmouse)
 	struct byd_data *priv = psmouse->private;
 
 	if (priv) {
-		timer_delete(&priv->timer);
+		timer_shutdown_sync(&priv->timer);
 		kfree(psmouse->private);
 		psmouse->private = NULL;
 	}

From: Linmao Li <[email protected]>

[ Upstream commit c83e79c0842ed29860648bcce5022ef0ba5001c6 ]

byd_disconnect() uses timer_delete() before freeing the driver's private data. This does not wait for a running byd_clear_touch() callback, which dereferences the private data and its psmouse pointer. A callback racing with disconnect can therefore access the private data after it has been freed. The timer can also still be re-armed by byd_process_byte() while the disconnect is in progress.

Use timer_shutdown_sync() before freeing the private data: it waits for a running callback and turns any later re-arm attempt into a no-op.

---
 drivers/input/mouse/byd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 221a553f45cd8..cb49f38883020 100644
@@ -426,7 +426,7 @@ static void byd_disconnect(struct psmouse *psmouse)
 	struct byd_data *priv = psmouse->private;
 
 	if (priv) {
-		del_timer(&priv->timer);
+		timer_shutdown_sync(&priv->timer);
 		kfree(psmouse->private);
 		psmouse->private = NULL;
 	}

2.53.0