rsi: Fix NULL pointer dereference in kmalloc

kmalloc can fail in rsi_register_rates_channels but memcpy still attempts
to write to channels. The patch replaces these calls with kmemdup and
passes the error upstream.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/rsi/rsi_91x_mac80211.c

@@ -188,27 +188,27 @@ bool rsi_is_cipher_wep(struct rsi_common *common)
  * @adapter: Pointer to the adapter structure.
  * @band: Operating band to be set.
  *
- * Return: None.
+ * Return: int - 0 on success, negative error on failure.
  */
-static void rsi_register_rates_channels(struct rsi_hw *adapter, int band)
+static int rsi_register_rates_channels(struct rsi_hw *adapter, int band)
 {
 	struct ieee80211_supported_band *sbands = &adapter->sbands[band];
 	void *channels = NULL;
 
 	if (band == NL80211_BAND_2GHZ) {
-		channels = kmalloc(sizeof(rsi_2ghz_channels), GFP_KERNEL);
-		memcpy(channels,
-		       rsi_2ghz_channels,
-		       sizeof(rsi_2ghz_channels));
+		channels = kmemdup(rsi_2ghz_channels, sizeof(rsi_2ghz_channels),
+				   GFP_KERNEL);
+		if (!channels)
+			return -ENOMEM;
 		sbands->band = NL80211_BAND_2GHZ;
 		sbands->n_channels = ARRAY_SIZE(rsi_2ghz_channels);
 		sbands->bitrates = rsi_rates;
 		sbands->n_bitrates = ARRAY_SIZE(rsi_rates);
 	} else {
-		channels = kmalloc(sizeof(rsi_5ghz_channels), GFP_KERNEL);
-		memcpy(channels,
-		       rsi_5ghz_channels,
-		       sizeof(rsi_5ghz_channels));
+		channels = kmemdup(rsi_5ghz_channels, sizeof(rsi_5ghz_channels),
+				   GFP_KERNEL);
+		if (!channels)
+			return -ENOMEM;
 		sbands->band = NL80211_BAND_5GHZ;
 		sbands->n_channels = ARRAY_SIZE(rsi_5ghz_channels);
 		sbands->bitrates = &rsi_rates[4];
@@ -227,6 +227,7 @@ static void rsi_register_rates_channels(struct rsi_hw *adapter, int band)
 	sbands->ht_cap.mcs.rx_mask[0] = 0xff;
 	sbands->ht_cap.mcs.tx_params = IEEE80211_HT_MCS_TX_DEFINED;
 	/* sbands->ht_cap.mcs.rx_highest = 0x82; */
+	return 0;
 }
 
 static int rsi_mac80211_hw_scan_start(struct ieee80211_hw *hw,
@@ -2064,11 +2065,16 @@ int rsi_mac80211_attach(struct rsi_common *common)
 	wiphy->available_antennas_rx = 1;
 	wiphy->available_antennas_tx = 1;
 
-	rsi_register_rates_channels(adapter, NL80211_BAND_2GHZ);
+	status = rsi_register_rates_channels(adapter, NL80211_BAND_2GHZ);
+	if (status)
+		return status;
 	wiphy->bands[NL80211_BAND_2GHZ] =
 		&adapter->sbands[NL80211_BAND_2GHZ];
 	if (common->num_supp_bands > 1) {
-		rsi_register_rates_channels(adapter, NL80211_BAND_5GHZ);
+		status = rsi_register_rates_channels(adapter,
+						     NL80211_BAND_5GHZ);
+		if (status)
+			return status;
 		wiphy->bands[NL80211_BAND_5GHZ] =
 			&adapter->sbands[NL80211_BAND_5GHZ];
 	}