net: mwifiex: fix a NULL pointer dereference

In case dev_alloc_skb fails, the fix returns -ENOMEM to avoid
NULL pointer dereference.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/cmdevt.c

@@ -341,6 +341,12 @@ static int mwifiex_dnld_sleep_confirm_cmd(struct mwifiex_adapter *adapter)
 		sleep_cfm_tmp =
 			dev_alloc_skb(sizeof(struct mwifiex_opt_sleep_confirm)
 				      + MWIFIEX_TYPE_LEN);
+		if (!sleep_cfm_tmp) {
+			mwifiex_dbg(adapter, ERROR,
+				    "SLEEP_CFM: dev_alloc_skb failed\n");
+			return -ENOMEM;
+		}
+
 		skb_put(sleep_cfm_tmp, sizeof(struct mwifiex_opt_sleep_confirm)
 			+ MWIFIEX_TYPE_LEN);
 		put_unaligned_le32(MWIFIEX_USB_TYPE_CMD, sleep_cfm_tmp->data);