Fix bug #48504: tcp_debug_print_pcbs reads nonexisting tcp_pcb fields

src/core/tcp.c

@@ -2023,6 +2023,8 @@ void
 tcp_debug_print_pcbs(void)
 {
   struct tcp_pcb *pcb;
+  struct tcp_pcb_listen *pcbl;
+
   LWIP_DEBUGF(TCP_DEBUG, ("Active PCB states:\n"));
   for (pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
     LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
@@ -2030,13 +2032,13 @@ tcp_debug_print_pcbs(void)
                        pcb->snd_nxt, pcb->rcv_nxt));
     tcp_debug_print_state(pcb->state);
   }
+
   LWIP_DEBUGF(TCP_DEBUG, ("Listen PCB states:\n"));
-  for (pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) {
-    LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
-                       pcb->local_port, pcb->remote_port,
-                       pcb->snd_nxt, pcb->rcv_nxt));
-    tcp_debug_print_state(pcb->state);
+  for (pcbl = tcp_listen_pcbs.listen_pcbs; pcbl != NULL; pcbl = pcbl->next) {
+    LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F" ", pcbl->local_port));
+    tcp_debug_print_state(pcbl->state);
   }
+
   LWIP_DEBUGF(TCP_DEBUG, ("TIME-WAIT PCB states:\n"));
   for (pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
     LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",