rtlwifi: rtl8192c_common: rtl8192de: Check for allocation failures

In https://bugzilla.redhat.com/show_bug.cgi?id=771656, a kernel bug was
triggered due to a failed skb allocation that was not checked. This event
lead to an audit of all memory allocations in the complete rtlwifi family
of drivers. This patch fixes the rest.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rtlwifi/usb.c b/drivers/net/wireless/rtlwifi/usb.c
index 6ae1b21..4db06f6 100644
--- a/drivers/net/wireless/rtlwifi/usb.c
+++ b/drivers/net/wireless/rtlwifi/usb.c
@@ -520,12 +520,14 @@
 			u8 *pdata;
 
 			uskb = dev_alloc_skb(skb->len + 128);
-			memcpy(IEEE80211_SKB_RXCB(uskb), &rx_status,
-			       sizeof(rx_status));
-			pdata = (u8 *)skb_put(uskb, skb->len);
-			memcpy(pdata, skb->data, skb->len);
+			if (uskb) {	/* drop packet on allocation failure */
+				memcpy(IEEE80211_SKB_RXCB(uskb), &rx_status,
+				       sizeof(rx_status));
+				pdata = (u8 *)skb_put(uskb, skb->len);
+				memcpy(pdata, skb->data, skb->len);
+				ieee80211_rx_irqsafe(hw, uskb);
+			}
 			dev_kfree_skb_any(skb);
-			ieee80211_rx_irqsafe(hw, uskb);
 		} else {
 			dev_kfree_skb_any(skb);
 		}