[PATCH] staging: rtl8192e: Fix return type for implementation of ndo_start_xmit

[Philipp Hortmann]

CFI (Control Flow Integrity) is a safety feature allowing the system to
detect and react should a potential control flow hijacking occurs. In
particular, the Forward-Edge CFI protects indirect function calls by
ensuring the prototype of function that is actually called matches the
definition of the function hook.

Since Linux now supports CFI, it will be a good idea to fix mismatched
return type for implementation of hooks. Otherwise this would get
cought out by CFI and cause a panic.

Use enums from netdev_tx_t as return value instead, then change return
type to netdev_tx_t.

Suggested-by: Dan Carpenter <error27@xxxxxxxxx>
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@xxxxxxxxx>
---
Tested with rtl8192e
Transferred this patch over wlan connection of rtl8192e
---
 drivers/staging/rtl8192e/rtllib.h    |  2 +-
 drivers/staging/rtl8192e/rtllib_tx.c | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/rtl8192e/rtllib.h b/drivers/staging/rtl8192e/rtllib.h
index 0ecd81a81866..b4b606f552fb 100644
--- a/drivers/staging/rtl8192e/rtllib.h
+++ b/drivers/staging/rtl8192e/rtllib.h
@@ -1938,7 +1938,7 @@ int rtllib_encrypt_fragment(
 	struct sk_buff *frag,
 	int hdr_len);
 
-int rtllib_xmit(struct sk_buff *skb,  struct net_device *dev);
+netdev_tx_t rtllib_xmit(struct sk_buff *skb,  struct net_device *dev);
 void rtllib_txb_free(struct rtllib_txb *txb);
 
 /* rtllib_rx.c */
diff --git a/drivers/staging/rtl8192e/rtllib_tx.c b/drivers/staging/rtl8192e/rtllib_tx.c
index 42f81b23a144..ebcaf3bf22d6 100644
--- a/drivers/staging/rtl8192e/rtllib_tx.c
+++ b/drivers/staging/rtl8192e/rtllib_tx.c
@@ -543,7 +543,7 @@ static u8 rtllib_current_rate(struct rtllib_device *ieee)
 		return ieee->rate & 0x7F;
 }
 
-static int rtllib_xmit_inter(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t rtllib_xmit_inter(struct sk_buff *skb, struct net_device *dev)
 {
 	struct rtllib_device *ieee = (struct rtllib_device *)
 				     netdev_priv_rsl(dev);
@@ -946,23 +946,23 @@ static int rtllib_xmit_inter(struct sk_buff *skb, struct net_device *dev)
 			if ((*ieee->hard_start_xmit)(txb, dev) == 0) {
 				stats->tx_packets++;
 				stats->tx_bytes += le16_to_cpu(txb->payload_size);
-				return 0;
+				return NETDEV_TX_OK;
 			}
 			rtllib_txb_free(txb);
 		}
 	}
 
-	return 0;
+	return NETDEV_TX_OK;
 
  failed:
 	spin_unlock_irqrestore(&ieee->lock, flags);
 	netif_stop_queue(dev);
 	stats->tx_errors++;
-	return 1;
+	return NETDEV_TX_BUSY;
 
 }
 
-int rtllib_xmit(struct sk_buff *skb, struct net_device *dev)
+netdev_tx_t rtllib_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	memset(skb->cb, 0, sizeof(skb->cb));
 	return rtllib_xmit_inter(skb, dev);
-- 
2.37.2