1 files changed, 30 insertions, 34 deletions

diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 35a8dd35ed4e..c15441b5ff61 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -18,14 +18,14 @@
 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 				       netdev_features_t features)
 {
+	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
-	int ghl;
 	struct gre_base_hdr *greh;
 	u16 mac_offset = skb->mac_header;
-	int mac_len = skb->mac_len;
 	__be16 protocol = skb->protocol;
-	int tnl_hlen;
-	bool csum;
+	u16 mac_len = skb->mac_len;
+	int gre_offset, outer_hlen;
+	bool need_csum;
 
 	if (unlikely(skb_shinfo(skb)->gso_type &
 				~(SKB_GSO_TCPV4 |
@@ -42,64 +42,60 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 	if (!skb->encapsulation)
 		goto out;
 
-	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
+	if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
 		goto out;
 
-	greh = (struct gre_base_hdr *)skb_transport_header(skb);
-
-	ghl = skb_inner_mac_header(skb) - skb_transport_header(skb);
-	if (unlikely(ghl < sizeof(*greh)))
+	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
 		goto out;
 
-	csum = !!(greh->flags & GRE_CSUM);
-	if (csum)
-		skb->encap_hdr_csum = 1;
+	greh = (struct gre_base_hdr *)skb_transport_header(skb);
 
 	/* setup inner skb. */
 	skb->protocol = greh->protocol;
 	skb->encapsulation = 0;
-
-	if (unlikely(!pskb_may_pull(skb, ghl)))
-		goto out;
-
-	__skb_pull(skb, ghl);
+	__skb_pull(skb, tnl_hlen);
 	skb_reset_mac_header(skb);
 	skb_set_network_header(skb, skb_inner_network_offset(skb));
 	skb->mac_len = skb_inner_network_offset(skb);
 
+	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
+	skb->encap_hdr_csum = need_csum;
+
 	features &= skb->dev->hw_enc_features;
 
 	/* segment inner packet. */
 	segs = skb_mac_gso_segment(skb, features);
 	if (IS_ERR_OR_NULL(segs)) {
-		skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
+		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
+				     mac_len);
 		goto out;
 	}
 
+	outer_hlen = skb_tnl_header_len(skb);
+	gre_offset = outer_hlen - tnl_hlen;
 	skb = segs;
-	tnl_hlen = skb_tnl_header_len(skb);
 	do {
-		__skb_push(skb, ghl);
-		if (csum) {
-			__be32 *pcsum;
-
-			skb_reset_transport_header(skb);
-
-			greh = (struct gre_base_hdr *)
-			    skb_transport_header(skb);
-			pcsum = (__be32 *)(greh + 1);
-			*pcsum = 0;
-			*(__sum16 *)pcsum = gso_make_checksum(skb, 0);
-		}
-		__skb_push(skb, tnl_hlen - ghl);
+		__be32 *pcsum;
 
 		skb_reset_inner_headers(skb);
 		skb->encapsulation = 1;
 
-		skb_reset_mac_header(skb);
-		skb_set_network_header(skb, mac_len);
 		skb->mac_len = mac_len;
 		skb->protocol = protocol;
+
+		__skb_push(skb, outer_hlen);
+		skb_reset_mac_header(skb);
+		skb_set_network_header(skb, mac_len);
+		skb_set_transport_header(skb, gre_offset);
+
+		if (!need_csum)
+			continue;
+
+		greh = (struct gre_base_hdr *)skb_transport_header(skb);
+		pcsum = (__be32 *)(greh + 1);
+
+		*pcsum = 0;
+		*(__sum16 *)pcsum = gso_make_checksum(skb, 0);
 	} while ((skb = skb->next));
 out:
 	return segs;