From a9c2be51936e0e6ee0edc66533f8370f28d5d220 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 10 Mar 2026 22:39:36 -1000
Subject: [PATCH] Check socket type before accessing pcb.tcp union member

Move the NETCONN_TCP type check before the pcb.tcp null check
to avoid reading the wrong union member on non-TCP sockets.
---
 esphome/core/lwip_fast_select.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/esphome/core/lwip_fast_select.c b/esphome/core/lwip_fast_select.c
index ca693494670..a695fa396bc 100644
--- a/esphome/core/lwip_fast_select.c
+++ b/esphome/core/lwip_fast_select.c
@@ -218,10 +218,12 @@ void esphome_lwip_hook_socket(struct lwip_sock *sock) {
 }
 
 bool esphome_lwip_set_nodelay(struct lwip_sock *sock, bool enable) {
-  if (sock == NULL || sock->conn == NULL || sock->conn->pcb.tcp == NULL)
+  if (sock == NULL || sock->conn == NULL)
     return false;
   if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_TCP)
     return false;
+  if (sock->conn->pcb.tcp == NULL)
+    return false;
   if (enable) {
     tcp_nagle_disable(sock->conn->pcb.tcp);
   } else {