Merge branch 'sch_cake-fixes'

Toke Høiland-Jørgensen says:

====================
sched: A few small fixes for sch_cake

Kevin noticed a few issues with the way CAKE reads the skb protocol and the IP
diffserv fields. This series fixes those two issues, and should probably go to
in 4.19 as well. However, the previous refactoring patch means they don't apply
as-is; I can send a follow-up directly to stable if that's OK with you?
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/sch_cake.c

@@ -1517,16 +1517,27 @@ static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free)
 
 static u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)
 {
+	int wlen = skb_network_offset(skb);
 	u8 dscp;
 
-	switch (skb->protocol) {
+	switch (tc_skb_protocol(skb)) {
 	case htons(ETH_P_IP):
+		wlen += sizeof(struct iphdr);
+		if (!pskb_may_pull(skb, wlen) ||
+		    skb_try_make_writable(skb, wlen))
+			return 0;
+
 		dscp = ipv4_get_dsfield(ip_hdr(skb)) >> 2;
 		if (wash && dscp)
 			ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);
 		return dscp;
 
 	case htons(ETH_P_IPV6):
+		wlen += sizeof(struct ipv6hdr);
+		if (!pskb_may_pull(skb, wlen) ||
+		    skb_try_make_writable(skb, wlen))
+			return 0;
+
 		dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> 2;
 		if (wash && dscp)
 			ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);