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[rp2040] Fix W5500 Ethernet pbuf corruption by mirroring LWIPMutex semantics

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The previous LwIPLock for RP2040+Ethernet only called
ethernet_arch_lwip_begin/end, taking the async_context lock but never
bumping arduino-pico's __inLWIP counter. The W5500 GPIO IRQ path
(LwipIntfDev::_irq) checks __inLWIP to decide whether to defer packet
processing; with __inLWIP == 0 it would proceed to run _lwipCallback
immediately from IRQ context even while the main thread held the
async_context lock, re-entering lwIP and corrupting pbuf chains.

The corruption surfaced later as the pbuf_cat assertion
"p->tot_len == p->len (of last pbuf in chain)" panicking the device
on wiznet-w5500-evb-pico boards configured with an interrupt pin.

Mirror arduino-pico's LWIPMutex (cores/rp2040/lwip_wrap.h) exactly:
bump __inLWIP, take the lock, and on release re-unmask any GPIO IRQs
that were deferred while we held it (__needsIRQEN). We can't write
`using LwIPLock = LWIPMutex;` in core/helpers.h because pulling
lwip_wrap.h there transitively poisons many translation units with
lwIP types in an order that breaks err_t resolution, so the body is
inlined in the rp2040 helpers.cpp where the include is scoped.
This commit is contained in:
J. Nick Koston
2026-04-09 17:42:33 -10:00
parent ec420d5792
commit df51f4e371
1 changed files with 25 additions and 6 deletions
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esphome/components/rp2040/helpers.cpp
+25 -6
View File
@@ -9,7 +9,7 @@
#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)
#include <lwip_wrap.h> // For LWIPMutex — LwIPLock delegates to it (see below)
#include "esphome/components/ethernet/ethernet_component.h"
#endif
#include <hardware/structs/rosc.h>
@@ -43,9 +43,18 @@ IRAM_ATTR InterruptLock::~InterruptLock() { restore_interrupts(state_); }
// 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.
// WiFi uses cyw43_arch_lwip_begin/end.
//
// For wired Ethernet, taking only the async_context lock is NOT enough. The
// W5500 GPIO IRQ path (LwipIntfDev::_irq) checks arduino-pico's `__inLWIP`
// counter to decide whether to defer packet processing. If we hold the
// async_context lock without bumping `__inLWIP`, an interrupt-driven packet
// arrival re-enters lwIP from IRQ context and corrupts pbufs (the `pbuf_cat`
// assertion crash on wiznet-w5500-evb-pico). We mirror arduino-pico's
// LWIPMutex (cores/rp2040/lwip_wrap.h) exactly: bump `__inLWIP`, take the
// lock, and on release re-unmask any GPIO IRQs that were deferred while we
// held it. We can't `using LwIPLock = LWIPMutex;` in helpers.h because
// pulling lwip_wrap.h there poisons many TUs with lwIP types.
//
// When neither WiFi nor Ethernet is configured, this is a no-op since
// there's no network stack and no lwip callbacks to race with.
@@ -53,8 +62,18 @@ IRAM_ATTR InterruptLock::~InterruptLock() { restore_interrupts(state_); }
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(); }
LwIPLock::LwIPLock() {
__inLWIP++;
ethernet_arch_lwip_begin();
}
LwIPLock::~LwIPLock() {
ethernet_arch_lwip_end();
__inLWIP--;
if (__needsIRQEN && !__inLWIP) {
__needsIRQEN = false;
ethernet_arch_lwip_gpio_unmask();
}
}
#else
LwIPLock::LwIPLock() {}
LwIPLock::~LwIPLock() {}