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Commit c87b4ecd authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by David S. Miller
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sch_cake: Make sure we can write the IP header before changing DSCP bits 



There is not actually any guarantee that the IP headers are valid before we
access the DSCP bits of the packets. Fix this using the same approach taken
in sch_dsmark.

Reported-by: default avatarKevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b2100cc5

net/sched/sch_cake.c

+11 −0
Original line number Diff line number Diff line
@@ -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 (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);