[PATCH net-next 1/5] bridge: Use direct pointer in br_is_nd_neigh_msg()

[Danielle Ratson]

Both callers of br_is_nd_neigh_msg() already call pskb_may_pull() to
ensure sizeof(struct ipv6hdr) + sizeof(struct nd_msg) bytes are in the
linear area before invoking this function. The skb_header_pointer()
call and its fallback buffer are therefore unnecessary.

Replace skb_header_pointer() with a direct cast to ipv6_hdr(skb) + 1
and drop the now-unused 'msg' parameter and its corresponding stack
buffer from all callers.

Reviewed-by: Petr Machata <petrm@xxxxxxxxxx>
Signed-off-by: Danielle Ratson <danieller@xxxxxxxxxx>
---
 net/bridge/br_arp_nd_proxy.c | 9 ++-------
 net/bridge/br_device.c       | 4 ++--
 net/bridge/br_input.c        | 4 ++--
 net/bridge/br_private.h      | 2 +-
 4 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/net/bridge/br_arp_nd_proxy.c b/net/bridge/br_arp_nd_proxy.c
index 23eb6931a2b4..db08c3272001 100644
--- a/net/bridge/br_arp_nd_proxy.c
+++ b/net/bridge/br_arp_nd_proxy.c
@@ -234,14 +234,9 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 #endif
 
 #if IS_ENABLED(CONFIG_IPV6)
-struct nd_msg *br_is_nd_neigh_msg(const struct sk_buff *skb, struct nd_msg *msg)
+struct nd_msg *br_is_nd_neigh_msg(const struct sk_buff *skb)
 {
-	struct nd_msg *m;
-
-	m = skb_header_pointer(skb, skb_network_offset(skb) +
-			       sizeof(struct ipv6hdr), sizeof(*msg), msg);
-	if (!m)
-		return NULL;
+	struct nd_msg *m = (struct nd_msg *)(ipv6_hdr(skb) + 1);
 
 	if (m->icmph.icmp6_code != 0 ||
 	    (m->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION &&
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index e7f343ab22d3..ff55dab73632 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -80,9 +80,9 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 		   pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 				 sizeof(struct nd_msg)) &&
 		   ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
-			struct nd_msg *msg, _msg;
+			struct nd_msg *msg;
 
-			msg = br_is_nd_neigh_msg(skb, &_msg);
+			msg = br_is_nd_neigh_msg(skb);
 			if (msg)
 				br_do_suppress_nd(skb, br, vid, NULL, msg);
 	}
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index ddb8f002a40e..d87a5f9fa92b 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -176,9 +176,9 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		   pskb_may_pull(skb, sizeof(struct ipv6hdr) +
 				 sizeof(struct nd_msg)) &&
 		   ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
-			struct nd_msg *msg, _msg;
+			struct nd_msg *msg;
 
-			msg = br_is_nd_neigh_msg(skb, &_msg);
+			msg = br_is_nd_neigh_msg(skb);
 			if (msg)
 				br_do_suppress_nd(skb, br, vid, p, msg);
 	}
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index f8f77a2d4891..a51246747537 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -2365,7 +2365,7 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
 			      u16 vid, struct net_bridge_port *p);
 void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
 		       u16 vid, struct net_bridge_port *p, struct nd_msg *msg);
-struct nd_msg *br_is_nd_neigh_msg(const struct sk_buff *skb, struct nd_msg *m);
+struct nd_msg *br_is_nd_neigh_msg(const struct sk_buff *skb);
 bool br_is_neigh_suppress_enabled(const struct net_bridge_port *p, u16 vid);
 bool br_is_neigh_forward_grat_enabled(const struct net_bridge_port *p, u16 vid);
 #endif
-- 
2.54.0