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/pci.c b/drivers/net/wireless/rtlwifi/pci.c
index 3c4ae5d..8758b3d 100644
--- a/drivers/net/wireless/rtlwifi/pci.c
+++ b/drivers/net/wireless/rtlwifi/pci.c
@@ -652,6 +652,8 @@
 		return;
 
 	uskb = dev_alloc_skb(skb->len + 128);
+	if (!uskb)
+		return;		/* exit if allocation failed */
 	memcpy(IEEE80211_SKB_RXCB(uskb), &rx_status, sizeof(rx_status));
 	pdata = (u8 *)skb_put(uskb, skb->len);
 	memcpy(pdata, skb->data, skb->len);