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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 5.15 329/846] HID: hid-uclogic-params: Invalid parameter check in uclogic_params_get_str_desc
Date:   Mon, 24 Jan 2022 19:37:26 +0100
Message-Id: <20220124184112.258380417@linuxfoundation.org>
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From: José Expósito <jose.exposito89@gmail.com>

[ Upstream commit 0a94131d6920916ccb6a357037c535533af08819 ]

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: 1443827 ("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 3c10b858cf74c..3a83e2c39b4fb 100644
--- a/drivers/hid/hid-uclogic-params.c
+++ b/drivers/hid/hid-uclogic-params.c
@@ -66,7 +66,7 @@ static int uclogic_params_get_str_desc(__u8 **pbuf, struct hid_device *hdev,
 					__u8 idx, size_t len)
 {
 	int rc;
-	struct usb_device *udev = hid_to_usb_dev(hdev);
+	struct usb_device *udev;
 	__u8 *buf = NULL;
 
 	/* Check arguments */
@@ -75,6 +75,8 @@ static int uclogic_params_get_str_desc(__u8 **pbuf, struct hid_device *hdev,
 		goto cleanup;
 	}
 
+	udev = hid_to_usb_dev(hdev);
+
 	buf = kmalloc(len, GFP_KERNEL);
 	if (buf == NULL) {
 		rc = -ENOMEM;
-- 
2.34.1