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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,
        =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jose.exposito89@gmail.com>,
        Jiri Kosina <jkosina@suse.cz>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 331/846] HID: hid-uclogic-params: Invalid parameter check in uclogic_params_frame_init_v1_buttonpad
Date:   Mon, 24 Jan 2022 19:37:28 +0100
Message-Id: <20220124184112.325119198@linuxfoundation.org>
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From: José Expósito <jose.exposito89@gmail.com>

[ Upstream commit aa320fdbbbb482c19100f51461bd0069753ce3d7 ]

The function performs a check on the hdev input parameters, however, it
is used before the check.

Initialize the udev variable after the sanity check to avoid a
possible NULL pointer dereference.

Fixes: 9614219e9310e ("HID: uclogic: Extract tablet parameter discovery into a module")
Addresses-Coverity-ID: 1443763 ("Null pointer dereference")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-uclogic-params.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-uclogic-params.c b/drivers/hid/hid-uclogic-params.c
index 4136837e4d158..3e70f969fb849 100644
--- a/drivers/hid/hid-uclogic-params.c
+++ b/drivers/hid/hid-uclogic-params.c
@@ -452,7 +452,7 @@ static int uclogic_params_frame_init_v1_buttonpad(
 {
 	int rc;
 	bool found = false;
-	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
+	struct usb_device *usb_dev;
 	char *str_buf = NULL;
 	const size_t str_len = 16;
 
@@ -462,6 +462,8 @@ static int uclogic_params_frame_init_v1_buttonpad(
 		goto cleanup;
 	}
 
+	usb_dev = hid_to_usb_dev(hdev);
+
 	/*
 	 * Enable generic button mode
 	 */
-- 
2.34.1