lib,rlc_am_nr: fix processing of ACKs

lib/src/rlc/rlc_am_nr.cc

@@ -239,19 +239,23 @@ void rlc_am_nr_tx::handle_control_pdu(uint8_t* payload, uint32_t nof_bytes)
    */
   // Process ACKs
   uint32_t stop_sn = status.N_nack == 0
-                         ? st.tx_next
-                         : status.nacks[0].nack_sn; // Stop processing ACKs at the first NACK, if it exists.
-  if (status.ack_sn >= st.tx_next_ack) {
+                         ? status.ack_sn
+                         : status.nacks[0].nack_sn - 1; // Stop processing ACKs at the first NACK, if it exists.
+  if (stop_sn > st.tx_next) {
+    logger->error("Rx'ed ACK or NACK larger than TX_NEXT. Ignoring status report");
+    return;
+  }
   for (uint32_t sn = st.tx_next_ack; sn < stop_sn; sn++) {
     if (tx_window.has_sn(sn)) {
       tx_window.remove_pdu(sn);
       st.tx_next_ack = sn + 1;
+      // TODO notify PDCP
     } else {
       logger->error("Missing ACKed SN from TX window");
       break;
     }
   }
-  }
+
   // Process N_acks
   for (uint32_t nack_idx = 0; nack_idx < status.N_nack; nack_idx++) {
     if (st.tx_next_ack <= status.nacks[nack_idx].nack_sn && status.nacks[nack_idx].nack_sn <= st.tx_next) {