From 55b9d8142977dcba03a6b701db6d20ec5a4ecf70 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sun, 8 Mar 2026 01:15:33 -1000
Subject: [PATCH] Add diagnostic message before abort on buffer overflow

---
 esphome/components/rp2040/printf_stubs.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/esphome/components/rp2040/printf_stubs.cpp b/esphome/components/rp2040/printf_stubs.cpp
index 83d916cd2c9..c2174a1dece 100644
--- a/esphome/components/rp2040/printf_stubs.cpp
+++ b/esphome/components/rp2040/printf_stubs.cpp
@@ -32,6 +32,9 @@ static int write_printf_buffer(FILE *stream, char *buf, int len) {
   size_t write_len = len;
   if (write_len >= PRINTF_BUFFER_SIZE) {
     fwrite(buf, 1, PRINTF_BUFFER_SIZE - 1, stream);
+    // Use fwrite for the message to avoid recursive __wrap_printf call
+    static const char msg[] = "\nprintf buffer overflow\n";
+    fwrite(msg, 1, sizeof(msg) - 1, stream);
     abort();
   }
   if (fwrite(buf, 1, write_len, stream) < write_len || ferror(stream)) {