When collecting TCP flags we check that the IP header indicates that
a TCP header is present but not that the packet is actually long
enough to contain the header. This adds a check to prevent reading
off the end of the packet.
In practice, this is only likely to result in reading of bad data and
not a crash due to the presence of struct skb_shared_info at the end
of the packet.
Signed-off-by: Jesse Gross <je...@nicira.com>
---
net/openvswitch/flow.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 1252c30..2a11ec2 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -183,7 +183,8 @@ void ovs_flow_used(struct sw_flow *flow, struct sk_buff
*skb)
u8 tcp_flags = 0;
if (flow->key.eth.type == htons(ETH_P_IP) &&
- flow->key.ip.proto == IPPROTO_TCP) {
+ flow->key.ip.proto == IPPROTO_TCP &&
+ likely(skb->len >= skb_transport_offset(skb) + sizeof(struct
tcphdr))) {
u8 *tcp = (u8 *)tcp_hdr(skb);
tcp_flags = *(tcp + TCP_FLAGS_OFFSET) & TCP_FLAG_MASK;
}
--
1.7.9.5
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