linux-kernel - [PATCH v2] rsi: Fix NULL pointer dereference in kmalloc

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Date:   Sat, 23 Mar 2019 15:49:16 -0500
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Amitkumar Karwar <amitkarwar@...il.com>,
        Siva Rebbagondla <siva8118@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] 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@....edu>

---
v1: Fix kmalloc failure by displaying a message. Change it to return the
error upstream, suggested by Joe, Johannes.
---
 drivers/net/wireless/rsi/rsi_91x_mac80211.c | 30 ++++++++++++---------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/rsi/rsi_91x_mac80211.c b/drivers/net/wireless/rsi/rsi_91x_mac80211.c
index 831046e760f8..49df3bb08d41 100644
--- a/drivers/net/wireless/rsi/rsi_91x_mac80211.c
+++ b/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];
 	}
-- 
2.17.1