staging: rtl8192e: use memdup_user to simplify code

Use memdup_user rather than duplicating its implementation. This patch
fixes the following coccinelle warnings:

drivers/staging/rtl8192e/rtl8192e/rtl_core.c:2598:8-15: WARNING opportunity for memdup_user
drivers/staging/rtl8192e/rtllib_softmac.c:3594:9-16: WARNING opportunity for memdup_user
Signed-off-by: Teodora Baluta <teobaluta@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192e/rtl8192e/rtl_core.c

@@ -2593,14 +2593,9 @@ static int rtl8192_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 			goto out;
 		}
 
-		ipw = kmalloc(p->length, GFP_KERNEL);
-		if (ipw == NULL) {
-			ret = -ENOMEM;
-			goto out;
-		}
-		if (copy_from_user(ipw, p->pointer, p->length)) {
-			kfree(ipw);
-			ret = -EFAULT;
+		ipw = memdup_user(p->pointer, p->length);
+		if (IS_ERR(ipw)) {
+			ret = PTR_ERR(ipw);
 			goto out;
 		}
 

drivers/staging/rtl8192e/rtllib_softmac.c

@@ -3590,14 +3590,9 @@ int rtllib_wpa_supplicant_ioctl(struct rtllib_device *ieee, struct iw_point *p,
 		goto out;
 	}
 
-	param = kmalloc(p->length, GFP_KERNEL);
-	if (param == NULL) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	if (copy_from_user(param, p->pointer, p->length)) {
-		kfree(param);
-		ret = -EFAULT;
+	param = memdup_user(p->pointer, p->length);
+	if (IS_ERR(param)) {
+		ret = PTR_ERR(param);
 		goto out;
 	}