From: Eric Dumazet <edumazet@google.com>
Date: Thu, 7 May 2020 09:32:21 -0700
Subject: netpoll: accept NULL np argument in netpoll_send_skb()
Patch-mainline: v5.8-rc1
Git-commit: f78ed2204db9fc35b545d693865bddbe0149aa1f
References: bsc#1176447

netpoll_send_skb() callers seem to leak skb if
the np pointer is NULL. While this should not happen, we
can make the code more robust.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/macvlan.c   |    5 ++---
 include/linux/if_team.h |    5 +----
 include/net/bonding.h   |    5 +----
 net/8021q/vlan_dev.c    |    5 ++---
 net/bridge/br_private.h |    5 +----
 net/core/netpoll.c      |   11 ++++++++---
 net/dsa/slave.c         |    5 ++---
 7 files changed, 17 insertions(+), 24 deletions(-)

--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -541,12 +541,11 @@ xmit_world:
 static inline netdev_tx_t macvlan_netpoll_send_skb(struct macvlan_dev *vlan, struct sk_buff *skb)
 {
 #ifdef CONFIG_NET_POLL_CONTROLLER
-	if (vlan->netpoll)
-		netpoll_send_skb(vlan->netpoll, skb);
+	return netpoll_send_skb(vlan->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static netdev_tx_t macvlan_start_xmit(struct sk_buff *skb,
--- a/include/linux/if_team.h
+++ b/include/linux/if_team.h
@@ -102,10 +102,7 @@ static inline bool team_port_dev_txable(
 static inline void team_netpoll_send_skb(struct team_port *port,
 					 struct sk_buff *skb)
 {
-	struct netpoll *np = port->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	netpoll_send_skb(port->np, skb);
 }
 #else
 static inline void team_netpoll_send_skb(struct team_port *port,
--- a/include/net/bonding.h
+++ b/include/net/bonding.h
@@ -507,10 +507,7 @@ static inline unsigned long slave_last_r
 static inline void bond_netpoll_send_skb(const struct slave *slave,
 					 struct sk_buff *skb)
 {
-	struct netpoll *np = slave->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	netpoll_send_skb(slave->np, skb);
 }
 #else
 static inline void bond_netpoll_send_skb(const struct slave *slave,
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -88,12 +88,11 @@ static int vlan_dev_hard_header(struct s
 static inline netdev_tx_t vlan_netpoll_send_skb(struct vlan_dev_priv *vlan, struct sk_buff *skb)
 {
 #ifdef CONFIG_NET_POLL_CONTROLLER
-	if (vlan->netpoll)
-		netpoll_send_skb(vlan->netpoll, skb);
+	return netpoll_send_skb(vlan->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -529,10 +529,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *
 static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
 				       struct sk_buff *skb)
 {
-	struct netpoll *np = p->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	netpoll_send_skb(p->np, skb);
 }
 
 int br_netpoll_enable(struct net_bridge_port *p);
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -367,9 +367,14 @@ netdev_tx_t netpoll_send_skb(struct netp
 	unsigned long flags;
 	netdev_tx_t ret;
 
-	local_irq_save(flags);
-	ret = __netpoll_send_skb(np, skb);
-	local_irq_restore(flags);
+	if (unlikely(!np)) {
+		dev_kfree_skb_irq(skb);
+		ret = NET_XMIT_DROP;
+	} else {
+		local_irq_save(flags);
+		ret = __netpoll_send_skb(np, skb);
+		local_irq_restore(flags);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(netpoll_send_skb);
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -405,12 +405,11 @@ static inline netdev_tx_t dsa_slave_netp
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	struct dsa_slave_priv *p = netdev_priv(dev);
 
-	if (p->netpoll)
-		netpoll_send_skb(p->netpoll, skb);
+	return netpoll_send_skb(p->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static void dsa_skb_tx_timestamp(struct dsa_slave_priv *p,