diff --git a/components/lwip/core/tcp.c b/components/lwip/core/tcp.c index 920523e45d..35649f12fa 100644 --- a/components/lwip/core/tcp.c +++ b/components/lwip/core/tcp.c @@ -1751,19 +1751,31 @@ tcp_pcb_purge(struct tcp_pcb *pcb) if (pcb->state == SYN_RCVD) { /* Need to find the corresponding listen_pcb and decrease its accepts_pending */ struct tcp_pcb_listen *lpcb; - LWIP_ASSERT("tcp_pcb_purge: pcb->state == SYN_RCVD but tcp_listen_pcbs is NULL", - tcp_listen_pcbs.listen_pcbs != NULL); - for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) { - if ((lpcb->local_port == pcb->local_port) && - (IP_IS_V6_VAL(pcb->local_ip) == IP_IS_V6_VAL(lpcb->local_ip)) && - (ip_addr_isany(&lpcb->local_ip) || - ip_addr_cmp(&pcb->local_ip, &lpcb->local_ip))) { - /* port and address of the listen pcb match the timed-out pcb */ - LWIP_ASSERT("tcp_pcb_purge: listen pcb does not have accepts pending", - lpcb->accepts_pending > 0); - lpcb->accepts_pending--; - break; + + /* + * The official LWIP will assert the system if tcp_listen_pcbs.listen_pcbs is NULL, it's a bug. + * + * Considering following scenario: + * 1. On TCP server side, one of TCP pcb is in SYNC_RECV state and is waiting for TCP ACK from TCP client. + * 2. The TCP server is closed by application, which causes the tcp_listen_pcbs.listen_pcbs to become NULL. + * 3. When SYNC_RECV state timeout (20s by default), tcp_pcb_purge() is called in tcp_slowtmr(), it asserts + * the system. + * This is a normal scenario, should NOT assert the system. So just remove it. + * + */ + if (tcp_listen_pcbs.listen_pcbs) { + for (lpcb = tcp_listen_pcbs.listen_pcbs; lpcb != NULL; lpcb = lpcb->next) { + if ((lpcb->local_port == pcb->local_port) && + (IP_IS_V6_VAL(pcb->local_ip) == IP_IS_V6_VAL(lpcb->local_ip)) && + (ip_addr_isany(&lpcb->local_ip) || + ip_addr_cmp(&pcb->local_ip, &lpcb->local_ip))) { + /* port and address of the listen pcb match the timed-out pcb */ + LWIP_ASSERT("tcp_pcb_purge: listen pcb does not have accepts pending", + lpcb->accepts_pending > 0); + lpcb->accepts_pending--; + break; } + } } } #endif /* TCP_LISTEN_BACKLOG */