From 4b4f6cecca446abcb686c6e6c451d4f1ec1a7497 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Mon, 17 May 2021 12:04:30 +0200
Subject: [PATCH] HID: magicmouse: fix NULL-deref on disconnect
Git-commit: 4b4f6cecca446abcb686c6e6c451d4f1ec1a7497
Patch-mainline: v5.13-rc5
References: git-fixes

Commit 9d7b18668956 ("HID: magicmouse: add support for Apple Magic
Trackpad 2") added a sanity check for an Apple trackpad but returned
success instead of -ENODEV when the check failed. This means that the
remove callback will dereference the never-initialised driver data
pointer when the driver is later unbound (e.g. on USB disconnect).

Reported-by: syzbot+ee6f6e2e68886ca256a8@syzkaller.appspotmail.com
Fixes: 9d7b18668956 ("HID: magicmouse: add support for Apple Magic Trackpad 2")
Cc: stable@vger.kernel.org      # 4.20
Cc: Claudio Mettler <claudio@ponyfleisch.ch>
Cc: Marek Wyborski <marek.wyborski@emwesoft.com>
Cc: Sean O'Brien <seobrien@chromium.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/hid/hid-magicmouse.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index 097870e43cfe..8bcaee4ccae0 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -693,7 +693,7 @@ static int magicmouse_probe(struct hid_device *hdev,
 	if (id->vendor == USB_VENDOR_ID_APPLE &&
 	    id->product == USB_DEVICE_ID_APPLE_MAGICTRACKPAD2 &&
 	    hdev->type != HID_TYPE_USBMOUSE)
-		return 0;
+		return -ENODEV;
 
 	msc = devm_kzalloc(&hdev->dev, sizeof(*msc), GFP_KERNEL);
 	if (msc == NULL) {
-- 
2.26.2