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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+ee6f6e2e68886ca256a8@syzkaller.appspotmail.com,
        Claudio Mettler <claudio@ponyfleisch.ch>,
        Marek Wyborski <marek.wyborski@emwesoft.com>,
        Sean OBrien <seobrien@chromium.org>,
        Johan Hovold <johan@kernel.org>, Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH 5.12 108/161] HID: magicmouse: fix NULL-deref on disconnect
Date:   Tue,  8 Jun 2021 20:27:18 +0200
Message-Id: <20210608175949.118331682@linuxfoundation.org>
In-Reply-To: <20210608175945.476074951@linuxfoundation.org>
References: <20210608175945.476074951@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 4b4f6cecca446abcb686c6e6c451d4f1ec1a7497 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hid/hid-magicmouse.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -597,7 +597,7 @@ static int magicmouse_probe(struct hid_d
 	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) {