Merge branch 'net-fix-the-features-flag-in-sctp_gso_segment'

Xin Long says:

====================
net: fix the features flag in sctp_gso_segment

Patch 1/2 is to improve the code in skb_segment(), and it is needed
by Patch 2/2.
====================

Link: https://lore.kernel.org/r/cover.1610703289.git.lucien.xin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/skbuff.c

@@ -3894,12 +3894,8 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
 		}
 
 		hsize = skb_headlen(head_skb) - offset;
-		if (hsize < 0)
-			hsize = 0;
-		if (hsize > len || !sg)
-			hsize = len;
 
-		if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
+		if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
 		    (skb_headlen(list_skb) == len || sg)) {
 			BUG_ON(skb_headlen(list_skb) > len);
 
@@ -3942,6 +3938,11 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
 			skb_release_head_state(nskb);
 			__skb_push(nskb, doffset);
 		} else {
+			if (hsize > len || !sg)
+				hsize = len;
+			else if (hsize < 0)
+				hsize = 0;
+
 			nskb = __alloc_skb(hsize + doffset + headroom,
 					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
 					   NUMA_NO_NODE);

net/sctp/offload.c

@@ -68,7 +68,7 @@ static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
 		goto out;
 	}
 
-	segs = skb_segment(skb, features | NETIF_F_HW_CSUM | NETIF_F_SG);
+	segs = skb_segment(skb, (features | NETIF_F_HW_CSUM) & ~NETIF_F_SG);
 	if (IS_ERR(segs))
 		goto out;