From: Jesse Gross Date: Fri, 23 Mar 2012 20:14:51 +0000 (-0700) Subject: flow: Add length check when retrieving TCP flags. X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9c47b45a3bb56009bf2553c493d097eeadd7e5c2;p=openvswitch flow: Add length check when retrieving TCP flags. 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 Acked-by: Pravin B Shelar --- diff --git a/datapath/flow.c b/datapath/flow.c index fb4fc217..27a8f249 100644 --- a/datapath/flow.c +++ b/datapath/flow.c @@ -185,7 +185,8 @@ 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; } diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index e1dc725d..d73050a3 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -976,7 +976,8 @@ dp_netdev_flow_used(struct dp_netdev_flow *flow, struct flow *key, flow->used = time_msec(); flow->packet_count++; flow->byte_count += packet->size; - if (key->dl_type == htons(ETH_TYPE_IP) && key->nw_proto == IPPROTO_TCP) { + if (key->dl_type == htons(ETH_TYPE_IP) && + key->nw_proto == IPPROTO_TCP && packet->l7) { struct tcp_header *th = packet->l4; flow->tcp_ctl |= th->tcp_ctl; }