From c87b4ecdbe8db27867a7b7f840291cd843406bd7 Mon Sep 17 00:00:00 2001 From: Toke Høiland-Jørgensen Date: Thu, 4 Apr 2019 15:01:33 +0200 Subject: sch_cake: Make sure we can write the IP header before changing DSCP bits MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Kevin Darbyshire-Bryant Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- net/sched/sch_cake.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index a3b55e18df04..259d97bc2abd 100644 --- a/net/sched/sch_cake.c +++ b/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 (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); -- cgit v1.2.3-59-g8ed1b