Patch "net: mpls: Fix multipath selection for LSR use case" has been added to the 4.9-stable tree

@@ -98,18 +98,19 @@ bool mpls_pkt_too_big(const struct sk_bu
 }
 EXPORT_SYMBOL_GPL(mpls_pkt_too_big);
 
-static u32 mpls_multipath_hash(struct mpls_route *rt,
-			       struct sk_buff *skb, bool bos)
+static u32 mpls_multipath_hash(struct mpls_route *rt, struct sk_buff *skb)
 {
 	struct mpls_entry_decoded dec;
+	unsigned int mpls_hdr_len = 0;
 	struct mpls_shim_hdr *hdr;
 	bool eli_seen = false;
 	int label_index;
 	u32 hash = 0;
 
-	for (label_index = 0; label_index < MAX_MP_SELECT_LABELS && !bos;
+	for (label_index = 0; label_index < MAX_MP_SELECT_LABELS;
 	     label_index++) {
-		if (!pskb_may_pull(skb, sizeof(*hdr) * label_index))
+		mpls_hdr_len += sizeof(*hdr);
+		if (!pskb_may_pull(skb, mpls_hdr_len))
 			break;
 
 		/* Read and decode the current label */

@@ -134,37 +135,38 @@ static u32 mpls_multipath_hash(struct mp
 			eli_seen = true;
 		}
 
-		bos = dec.bos;
-		if (bos && pskb_may_pull(skb, sizeof(*hdr) * label_index +
-					 sizeof(struct iphdr))) {
+		if (!dec.bos)
+			continue;
+
+		/* found bottom label; does skb have room for a header? */
+		if (pskb_may_pull(skb, mpls_hdr_len + sizeof(struct iphdr))) {
 			const struct iphdr *v4hdr;
 
-			v4hdr = (const struct iphdr *)(mpls_hdr(skb) +
-						       label_index);
+			v4hdr = (const struct iphdr *)(hdr + 1);
 			if (v4hdr->version == 4) {
 				hash = jhash_3words(ntohl(v4hdr->saddr),
 						    ntohl(v4hdr->daddr),
 						    v4hdr->protocol, hash);
 			} else if (v4hdr->version == 6 &&
-				pskb_may_pull(skb, sizeof(*hdr) * label_index +
-					      sizeof(struct ipv6hdr))) {
+				   pskb_may_pull(skb, mpls_hdr_len +
+						 sizeof(struct ipv6hdr))) {
 				const struct ipv6hdr *v6hdr;
 
-				v6hdr = (const struct ipv6hdr *)(mpls_hdr(skb) +
-								label_index);
-
+				v6hdr = (const struct ipv6hdr *)(hdr + 1);
 				hash = __ipv6_addr_jhash(&v6hdr->saddr, hash);
 				hash = __ipv6_addr_jhash(&v6hdr->daddr, hash);
 				hash = jhash_1word(v6hdr->nexthdr, hash);
 			}
 		}
+
+		break;
 	}
 
 	return hash;
 }
 
 static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt,
-					     struct sk_buff *skb, bool bos)
+					     struct sk_buff *skb)
 {
 	int alive = ACCESS_ONCE(rt->rt_nhn_alive);
 	u32 hash = 0;

@@ -180,7 +182,7 @@ static struct mpls_nh *mpls_select_multi
 	if (alive <= 0)
 		return NULL;
 
-	hash = mpls_multipath_hash(rt, skb, bos);
+	hash = mpls_multipath_hash(rt, skb);
 	nh_index = hash % alive;
 	if (alive == rt->rt_nhn)
 		goto out;

@@ -278,17 +280,11 @@ static int mpls_forward(struct sk_buff *
 	hdr = mpls_hdr(skb);
 	dec = mpls_entry_decode(hdr);
 
-	/* Pop the label */
-	skb_pull(skb, sizeof(*hdr));
-	skb_reset_network_header(skb);
-
-	skb_orphan(skb);
-
 	rt = mpls_route_input_rcu(net, dec.label);
 	if (!rt)
 		goto drop;
 
-	nh = mpls_select_multipath(rt, skb, dec.bos);
+	nh = mpls_select_multipath(rt, skb);
 	if (!nh)
 		goto drop;
 

@@ -297,6 +293,12 @@ static int mpls_forward(struct sk_buff *
 	if (!mpls_output_possible(out_dev))
 		goto drop;
 
+	/* Pop the label */
+	skb_pull(skb, sizeof(*hdr));
+	skb_reset_network_header(skb);
+
+	skb_orphan(skb);
+
 	if (skb_warn_if_lro(skb))
 		goto drop;