From 3e4cb845858b7a6fce56c493421a6a65ffe0e76a Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 14 Mar 2026 15:41:09 -1000
Subject: [PATCH] adjust

---
 esphome/components/rp2040/helpers.cpp         | 22 +++++++++++++------
 .../components/socket/lwip_raw_tcp_impl.cpp   |  3 ++-
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/esphome/components/rp2040/helpers.cpp b/esphome/components/rp2040/helpers.cpp
index a9888eb7ae..5b033f4c9c 100644
--- a/esphome/components/rp2040/helpers.cpp
+++ b/esphome/components/rp2040/helpers.cpp
@@ -8,6 +8,8 @@
 #if defined(USE_WIFI)
 #include <WiFi.h>
 #include <pico/cyw43_arch.h>  // For cyw43_arch_lwip_begin/end (LwIPLock)
+#elif defined(USE_ETHERNET)
+#include <LwipEthernet.h>  // For ethernet_arch_lwip_begin/end (LwIPLock)
 #endif
 #include <hardware/structs/rosc.h>
 #include <hardware/sync.h>
@@ -40,18 +42,24 @@ bool random_bytes(uint8_t *data, size_t len) {
 IRAM_ATTR InterruptLock::InterruptLock() { state_ = save_and_disable_interrupts(); }
 IRAM_ATTR InterruptLock::~InterruptLock() { restore_interrupts(state_); }
 
-// On RP2040 (Pico W), arduino-pico sets PICO_CYW43_ARCH_THREADSAFE_BACKGROUND=1.
-// This means lwip callbacks run from a low-priority user IRQ context, not the
+// On RP2040, lwip callbacks run from a low-priority user IRQ context, not the
 // main loop (see low_priority_irq_handler() in pico-sdk
-// async_context_threadsafe_background.c). cyw43_arch_lwip_begin/end acquires the
-// async_context recursive mutex to prevent IRQ callbacks from firing during
-// critical sections. See esphome#10681.
+// async_context_threadsafe_background.c). This applies to both WiFi (CYW43) and
+// Ethernet (W5500) — both use async_context_threadsafe_background.
 //
-// When CYW43 is not available (non-WiFi RP2040 boards), LwIPLock is
-// defined inline as a no-op in helpers.h.
+// Without locking, recv_fn() from IRQ context races with read_locked_() on the
+// main loop, corrupting the shared rx_buf_ pbuf chain (use-after-free, pbuf_cat
+// assertion failures). See esphome#10681.
+//
+// WiFi uses cyw43_arch_lwip_begin/end; Ethernet uses ethernet_arch_lwip_begin/end.
+// Both acquire the async_context recursive mutex to prevent IRQ callbacks from
+// firing during critical sections.
 #if defined(USE_WIFI)
 LwIPLock::LwIPLock() { cyw43_arch_lwip_begin(); }
 LwIPLock::~LwIPLock() { cyw43_arch_lwip_end(); }
+#elif defined(USE_ETHERNET)
+LwIPLock::LwIPLock() { ethernet_arch_lwip_begin(); }
+LwIPLock::~LwIPLock() { ethernet_arch_lwip_end(); }
 #else
 LwIPLock::LwIPLock() {}
 LwIPLock::~LwIPLock() {}
diff --git a/esphome/components/socket/lwip_raw_tcp_impl.cpp b/esphome/components/socket/lwip_raw_tcp_impl.cpp
index 96328e68c7..3bcbd88085 100644
--- a/esphome/components/socket/lwip_raw_tcp_impl.cpp
+++ b/esphome/components/socket/lwip_raw_tcp_impl.cpp
@@ -130,7 +130,8 @@ void socket_wake() {
 // code (CONT context) — they never preempt each other, so no locking is needed.
 //
 // esphome::LwIPLock is the platform-provided RAII guard (see helpers.h/helpers.cpp).
-// On RP2040, it acquires cyw43_arch_lwip_begin/end. On ESP8266, it's a no-op.
+// On RP2040, it acquires cyw43_arch_lwip_begin/end (WiFi) or ethernet_arch_lwip_begin/end
+// (Ethernet). On ESP8266, it's a no-op.
 #define LWIP_LOCK() esphome::LwIPLock lwip_lock_guard  // NOLINT
 
 static const char *const TAG = "socket.lwip";