From 8fcaebb44a578e15504461537c2b8421f21d88c6 Mon Sep 17 00:00:00 2001
From: Benoit Blanchon <git@benoitblanchon.fr>
Date: Thu, 20 Jul 2023 14:57:44 +0200
Subject: [PATCH] Detect null slot id earlier in `VariantPoolList::getSlot()`

---
 src/ArduinoJson/Memory/VariantPoolImpl.hpp | 3 ++-
 src/ArduinoJson/Memory/VariantPoolList.hpp | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/ArduinoJson/Memory/VariantPoolImpl.hpp b/src/ArduinoJson/Memory/VariantPoolImpl.hpp
index c616efc3..91f703a1 100644
--- a/src/ArduinoJson/Memory/VariantPoolImpl.hpp
+++ b/src/ArduinoJson/Memory/VariantPoolImpl.hpp
@@ -42,7 +42,8 @@ inline SlotWithId VariantPool::allocSlot() {
 }
 
 inline VariantSlot* VariantPool::getSlot(SlotId id) const {
-  return id == NULL_SLOT ? nullptr : &slots_[id];
+  ARDUINOJSON_ASSERT(id < usage_);
+  return &slots_[id];
 }
 
 inline SlotCount VariantPool::usage() const {
diff --git a/src/ArduinoJson/Memory/VariantPoolList.hpp b/src/ArduinoJson/Memory/VariantPoolList.hpp
index c92768ef..0e7cf9f6 100644
--- a/src/ArduinoJson/Memory/VariantPoolList.hpp
+++ b/src/ArduinoJson/Memory/VariantPoolList.hpp
@@ -52,10 +52,11 @@ class VariantPoolList {
   void freeSlot(SlotWithId slot);
 
   VariantSlot* getSlot(SlotId id) const {
+    if (id == NULL_SLOT)
+      return nullptr;
     auto poolIndex = SlotId(id / ARDUINOJSON_POOL_CAPACITY);
     auto indexInPool = SlotId(id % ARDUINOJSON_POOL_CAPACITY);
-    if (poolIndex >= count_)
-      return nullptr;
+    ARDUINOJSON_ASSERT(poolIndex < count_);
     return pools_[poolIndex].getSlot(indexInPool);
   }