Input: joydev - use memdup_user() to duplicate memory from user-space

The memdup_user() helper function can be used to duplicate a memory region
from user-space to kernel-space. There is no need to open code the same
logic using kmalloc() and copy_from_user() instead. This was found with
make coccicheck that reported the following warning:

drivers/input/joydev.c:447:10-17: WARNING opportunity for memdup_user
drivers/input/joydev.c:483:10-17: WARNING opportunity for memdup_user
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/joydev.c

@@ -444,12 +444,9 @@ static int joydev_handle_JSIOCSAXMAP(struct joydev *joydev,
 	len = min(len, sizeof(joydev->abspam));
 
 	/* Validate the map. */
-	abspam = kmalloc(len, GFP_KERNEL);
-	if (!abspam)
-		return -ENOMEM;
-
-	if (copy_from_user(abspam, argp, len)) {
-		retval = -EFAULT;
+	abspam = memdup_user(argp, len);
+	if (IS_ERR(abspam)) {
+		retval = PTR_ERR(abspam);
 		goto out;
 	}
 
@@ -480,12 +477,9 @@ static int joydev_handle_JSIOCSBTNMAP(struct joydev *joydev,
 	len = min(len, sizeof(joydev->keypam));
 
 	/* Validate the map. */
-	keypam = kmalloc(len, GFP_KERNEL);
-	if (!keypam)
-		return -ENOMEM;
-
-	if (copy_from_user(keypam, argp, len)) {
-		retval = -EFAULT;
+	keypam = memdup_user(argp, len);
+	if (IS_ERR(keypam)) {
+		retval = PTR_ERR(keypam);
 		goto out;
 	}