1 files changed, 16 insertions, 12 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 814b9b8882a0..14db1e0b8a6e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -422,7 +422,7 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 
 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
-	struct net_device *dev = skb_dst(skb)->dev;
+	struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
 
 	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
 
@@ -430,7 +430,7 @@ int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 	skb->protocol = htons(ETH_P_IP);
 
 	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
-			    net, sk, skb, NULL, dev,
+			    net, sk, skb, indev, dev,
 			    ip_finish_output,
 			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 }
@@ -645,11 +645,12 @@ void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
 EXPORT_SYMBOL(ip_fraglist_prepare);
 
 void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
-		  unsigned int ll_rs, unsigned int mtu,
+		  unsigned int ll_rs, unsigned int mtu, bool DF,
 		  struct ip_frag_state *state)
 {
 	struct iphdr *iph = ip_hdr(skb);
 
+	state->DF = DF;
 	state->hlen = hlen;
 	state->ll_rs = ll_rs;
 	state->mtu = mtu;
@@ -668,9 +669,6 @@ static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
 	/* Copy the flags to each fragment. */
 	IPCB(to)->flags = IPCB(from)->flags;
 
-	if (IPCB(from)->flags & IPSKB_FRAG_PMTU)
-		state->iph->frag_off |= htons(IP_DF);
-
 	/* ANK: dirty, but effective trick. Upgrade options only if
 	 * the segment to be fragmented was THE FIRST (otherwise,
 	 * options are already fixed) and make it ONCE
@@ -738,6 +736,8 @@ struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
 	 */
 	iph = ip_hdr(skb2);
 	iph->frag_off = htons((state->offset >> 3));
+	if (state->DF)
+		iph->frag_off |= htons(IP_DF);
 
 	/*
 	 *	Added AC : If we are fragmenting a fragment that's not the
@@ -883,7 +883,8 @@ slow_path:
 	 *	Fragment the datagram.
 	 */
 
-	ip_frag_init(skb, hlen, ll_rs, mtu, &state);
+	ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
+		     &state);
 
 	/*
 	 *	Keep copying data until we run out.
@@ -1257,15 +1258,18 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
 		cork->addr = ipc->addr;
 	}
 
-	/*
-	 * We steal reference to this route, caller should not release it
-	 */
-	*rtp = NULL;
 	cork->fragsize = ip_sk_use_pmtu(sk) ?
-			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
+			 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
+
+	if (!inetdev_valid_mtu(cork->fragsize))
+		return -ENETUNREACH;
 
 	cork->gso_size = ipc->gso_size;
+
 	cork->dst = &rt->dst;
+	/* We stole this route, caller should not release it. */
+	*rtp = NULL;
+
 	cork->length = 0;
 	cork->ttl = ipc->ttl;
 	cork->tos = ipc->tos;