From e7c0619189e6a9df04f98b15e881655142fd67f3 Mon Sep 17 00:00:00 2001
From: Simon Goldschmidt <goldsimon@gmx.de>
Date: Tue, 12 Jun 2018 13:32:12 +0200
Subject: [PATCH] fix NULL checks (compiler error, tcp_rst allows pcb==NULL)

---
 src/core/tcp.c     | 5 ++++-
 src/core/tcp_out.c | 3 +--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/core/tcp.c b/src/core/tcp.c
index b97fbf69..0362aab5 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -1534,10 +1534,13 @@ tcp_txnow(void)
 err_t
 tcp_process_refused_data(struct tcp_pcb *pcb)
 {
+#if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
+  struct pbuf *rest;
+#endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
+
   LWIP_ERROR("tcp_process_refused_data: invalid pcb", pcb != NULL, return ERR_ARG);
 
 #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
-  struct pbuf *rest;
   while (pcb->refused_data != NULL)
 #endif /* TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
   {
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index 2ad19b91..91f56aad 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -1886,7 +1886,7 @@ tcp_output_fill_options(const struct tcp_pcb *pcb, struct pbuf *p, u8_t optflags
 #endif
 
 #if LWIP_TCP_SACK_OUT
-  if (num_sacks > 0) {
+  if (pcb && (num_sacks > 0)) {
     tcp_build_sack_option(pcb, opts, num_sacks);
     /* 1 word for SACKs header (including 2xNOP), and 2 words for each SACK */
     sacks_len = 1 + num_sacks * 2;
@@ -1979,7 +1979,6 @@ tcp_rst(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
   u16_t wnd;
   u8_t optlen;
 
-  LWIP_ASSERT("tcp_rst: invalid pcb", pcb != NULL);
   LWIP_ASSERT("tcp_rst: invalid local_ip", local_ip != NULL);
   LWIP_ASSERT("tcp_rst: invalid remote_ip", remote_ip != NULL);