From:   =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jose.exposito89@gmail.com>
To:     jikos@kernel.org
Cc:     benjamin.tissoires@redhat.com, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org, spbnick@gmail.com,
        =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jose.exposito89@gmail.com>
Subject: [PATCH 2/4] HID: hid-uclogic-params: Invalid parameter check in uclogic_params_get_str_desc
Date:   Wed,  5 Jan 2022 18:29:13 +0100
Message-Id: <20220105172915.131091-3-jose.exposito89@gmail.com>
In-Reply-To: <20220105172915.131091-1-jose.exposito89@gmail.com>
References: <20220105172915.131091-1-jose.exposito89@gmail.com>
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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>
---
 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 3c10b858cf74..3a83e2c39b4f 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;
-- 
2.25.1