tcp: properly validate acks between snd_nxt and una_max

Change-Id: I37af3cb5fe3fe8556acbf8350f88663dca9ca8a9
Signed-off-by: Florin Coras <fcoras@cisco.com>

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 4927031..e0139a4 100644 (file)
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -411,7 +411,8 @@ tcp_rcv_ack_no_cc (tcp_connection_t * tc, vlib_buffer_t * b, u32 * error)
   if (!(seq_leq (tc->snd_una, vnet_buffer (b)->tcp.ack_number)
        && seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_nxt)))
     {
-      if (seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_una_max))
+      if (seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_una_max)
+         && seq_gt (vnet_buffer (b)->tcp.ack_number, tc->snd_una))
        {
          tc->snd_nxt = vnet_buffer (b)->tcp.ack_number;
          goto acceptable;
@@ -1580,7 +1581,8 @@ tcp_rcv_ack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, vlib_buffer_t * b,
     {
       /* We've probably entered recovery and the peer still has some
        * of the data we've sent. Update snd_nxt and accept the ack */
-      if (seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_una_max))
+      if (seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_una_max)
+         && seq_gt (vnet_buffer (b)->tcp.ack_number, tc->snd_una))
        {
          tc->snd_nxt = vnet_buffer (b)->tcp.ack_number;
          goto process_ack;