1 files changed, 59 insertions, 18 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 08f574081315..8c61c27c1b28 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3656,6 +3656,10 @@ normal:
 		skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &
 					      SKBTX_SHARED_FRAG;
 
+		if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
+		    skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
+			goto err;
+
 		while (pos < offset + len) {
 			if (i >= nfrags) {
 				BUG_ON(skb_headlen(list_skb));
@@ -3667,6 +3671,11 @@ normal:
 
 				BUG_ON(!nfrags);
 
+				if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
+				    skb_zerocopy_clone(nskb, frag_skb,
+						       GFP_ATOMIC))
+					goto err;
+
 				list_skb = list_skb->next;
 			}
 
@@ -3678,11 +3687,6 @@ normal:
 				goto err;
 			}
 
-			if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
-				goto err;
-			if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
-				goto err;
-
 			*nskb_frag = *frag;
 			__skb_frag_ref(nskb_frag);
 			size = skb_frag_size(nskb_frag);
@@ -4910,37 +4914,74 @@ unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
 EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);
 
 /**
- * skb_gso_validate_mtu - Return in case such skb fits a given MTU
+ * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
  *
- * @skb: GSO skb
- * @mtu: MTU to validate against
+ * There are a couple of instances where we have a GSO skb, and we
+ * want to determine what size it would be after it is segmented.
  *
- * skb_gso_validate_mtu validates if a given skb will fit a wanted MTU
- * once split.
+ * We might want to check:
+ * -    L3+L4+payload size (e.g. IP forwarding)
+ * - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
+ *
+ * This is a helper to do that correctly considering GSO_BY_FRAGS.
+ *
+ * @seg_len: The segmented length (from skb_gso_*_seglen). In the
+ *           GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
+ *
+ * @max_len: The maximum permissible length.
+ *
+ * Returns true if the segmented length <= max length.
  */
-bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu)
-{
+static inline bool skb_gso_size_check(const struct sk_buff *skb,
+				      unsigned int seg_len,
+				      unsigned int max_len) {
 	const struct skb_shared_info *shinfo = skb_shinfo(skb);
 	const struct sk_buff *iter;
-	unsigned int hlen;
-
-	hlen = skb_gso_network_seglen(skb);
 
 	if (shinfo->gso_size != GSO_BY_FRAGS)
-		return hlen <= mtu;
+		return seg_len <= max_len;
 
 	/* Undo this so we can re-use header sizes */
-	hlen -= GSO_BY_FRAGS;
+	seg_len -= GSO_BY_FRAGS;
 
 	skb_walk_frags(skb, iter) {
-		if (hlen + skb_headlen(iter) > mtu)
+		if (seg_len + skb_headlen(iter) > max_len)
 			return false;
 	}
 
 	return true;
 }
+
+/**
+ * skb_gso_validate_mtu - Return in case such skb fits a given MTU
+ *
+ * @skb: GSO skb
+ * @mtu: MTU to validate against
+ *
+ * skb_gso_validate_mtu validates if a given skb will fit a wanted MTU
+ * once split.
+ */
+bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu)
+{
+	return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
+}
 EXPORT_SYMBOL_GPL(skb_gso_validate_mtu);
 
+/**
+ * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
+ *
+ * @skb: GSO skb
+ * @len: length to validate against
+ *
+ * skb_gso_validate_mac_len validates if a given skb will fit a wanted
+ * length once split, including L2, L3 and L4 headers and the payload.
+ */
+bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
+{
+	return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
+}
+EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
+
 static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
 {
 	if (skb_cow(skb, skb_headroom(skb)) < 0) {