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 <ke...@darbyshire-bryant.me.uk>
Signed-off-by: Toke Høiland-Jørgensen <t...@redhat.com>
---
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);
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