[PATCH 6.18 502/752] HID: magicmouse: Do not crash on missing msc->input

Sasha Levin
2026-02-28T17:55:16Z

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 7d4a25c6de0eb..91f621ceb924b 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -725,6 +725,11 @@ 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