From 6abc2efd961dda4af0332eabd5335453d7cd71d1 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Fri, 10 Oct 2025 11:18:57 -1000
Subject: [PATCH] [json] Fix PSRAM allocator dangling pointer crash (#11165)

---
 esphome/components/json/json_util.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/esphome/components/json/json_util.cpp b/esphome/components/json/json_util.cpp
index dbdf6e3486..869d29f92e 100644
--- a/esphome/components/json/json_util.cpp
+++ b/esphome/components/json/json_util.cpp
@@ -8,6 +8,13 @@ namespace json {
 
 static const char *const TAG = "json";
 
+#ifdef USE_PSRAM
+// Global allocator that outlives all JsonDocuments returned by parse_json()
+// This prevents dangling pointer issues when JsonDocuments are returned from functions
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables) - Must be mutable for ArduinoJson::Allocator
+static SpiRamAllocator global_json_allocator;
+#endif
+
 std::string build_json(const json_build_t &f) {
   // NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
   JsonBuilder builder;
@@ -33,8 +40,7 @@ JsonDocument parse_json(const uint8_t *data, size_t len) {
     return JsonObject();  // return unbound object
   }
 #ifdef USE_PSRAM
-  auto doc_allocator = SpiRamAllocator();
-  JsonDocument json_document(&doc_allocator);
+  JsonDocument json_document(&global_json_allocator);
 #else
   JsonDocument json_document;
 #endif