From: Toke Høiland-Jørgensen toke@redhat.com
[ Upstream commit c87b4ecdbe8db27867a7b7f840291cd843406bd7 ]
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 kevin@darbyshire-bryant.me.uk Signed-off-by: Toke Høiland-Jørgensen toke@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_cake.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1524,16 +1524,27 @@ static void cake_wash_diffserv(struct sk
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);