queue-5.10/hid-magicmouse-do-not-crash-on-missing-msc-input.patch

From 8fe867d44fb078b27e9760b47bfe366dde184f09 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 9 Jan 2026 11:57:14 +0100
Subject: HID: magicmouse: Do not crash on missing msc->input
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From: Günther Noack <gnoack@google.com>

[ Upstream commit 17abd396548035fbd6179ee1a431bd75d49676a7 ]

Fake USB devices can send their own report descriptors for which the
input_mapping() hook does not get called.  In this case, msc->input stays NULL,
leading to a crash at a later time.

Detect this condition in the input_configured() hook and reject the device.

This is not supposed to happen with actual magic mouse devices, but can be
provoked by imposing as a magic mouse USB device.

Cc: stable@vger.kernel.org
Signed-off-by: Günther Noack <gnoack@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-magicmouse.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index 28158d2f23523..afde78319b996 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -569,6 +569,11 @@ static int magicmouse_input_configured(struct hid_device *hdev,
 	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
 	int ret;
 
+	if (!msc->input) {
+		hid_err(hdev, "magicmouse setup input failed (no input)");
+		return -EINVAL;
+	}
+
 	ret = magicmouse_setup_input(msc->input, hdev);
 	if (ret) {
 		hid_err(hdev, "magicmouse setup input failed (%d)\n", ret);
-- 
2.51.0