[app] Fix DeferredAttributePersister memory leak (project-chip#31075)

* [app] Fix DeferredAttributePerister memory leak

ScopedMemoryBuffer's Release() method was used instead of
Free(). Add CHECK_RETURN_VALUE annotation to the Release()
method to prevent from making such a mistake in the future.

Signed-off-by: Damian Krolik <damian.krolik@nordicsemi.no>

* Code review

---------

Signed-off-by: Damian Krolik <damian.krolik@nordicsemi.no>

Author: Damian-Nordic

src/app/DeferredAttributePersistenceProvider.cpp

@@ -39,7 +39,7 @@ void DeferredAttribute::Flush(AttributePersistenceProvider & persister)
 {
     VerifyOrReturn(IsArmed());
     persister.WriteValue(mPath, ByteSpan(mValue.Get(), mValue.AllocatedSize()));
-    mValue.Release();
+    mValue.Free();
 }
 
 CHIP_ERROR DeferredAttributePersistenceProvider::WriteValue(const ConcreteAttributePath & aPath, const ByteSpan & aValue)

src/darwin/Framework/CHIP/MTRBaseDevice.mm

@@ -1142,8 +1142,8 @@ - (void)readAttributePaths:(NSArray<MTRAttributeRequestPath *> * _Nullable)attri
             //
             callback->AdoptReadClient(std::move(readClient));
             callback.release();
-            attributePathParamsList.Release();
-            eventPathParamsList.Release();
+            IgnoreUnusedVariable(attributePathParamsList.Release());
+            IgnoreUnusedVariable(eventPathParamsList.Release());
             return err;
         });
     std::move(*bridge).DispatchAction(self);

src/lib/support/ScopedBuffer.h

@@ -25,6 +25,7 @@
 #pragma once
 
 #include <lib/support/CHIPMem.h>
+#include <lib/support/CodeUtils.h>
 
 #include <type_traits>
 #include <utility>
@@ -84,10 +85,11 @@ class ScopedMemoryBufferBase
     const void * Ptr() const { return mBuffer; }
 
     /**
-     * Releases the undelying buffer. Buffer stops being managed and will not be
-     * auto-freed.
+     * Releases the underlying buffer.
+     *
+     * The buffer stops being managed and will not be auto-freed.
      */
-    void * Release()
+    CHECK_RETURN_VALUE void * Release()
     {
         void * buffer = mBuffer;
         mBuffer       = nullptr;
@@ -139,13 +141,18 @@ class ScopedMemoryBuffer : public Impl::ScopedMemoryBufferBase<MemoryManagement>
 
     static_assert(std::is_trivially_destructible<T>::value, "Destructors won't get run");
 
-    inline T * Get() { return static_cast<T *>(Base::Ptr()); }
-    inline T & operator[](size_t index) { return Get()[index]; }
+    T * Get() { return static_cast<T *>(Base::Ptr()); }
+    T & operator[](size_t index) { return Get()[index]; }
 
-    inline const T * Get() const { return static_cast<const T *>(Base::Ptr()); }
-    inline const T & operator[](size_t index) const { return Get()[index]; }
+    const T * Get() const { return static_cast<const T *>(Base::Ptr()); }
+    const T & operator[](size_t index) const { return Get()[index]; }
 
-    inline T * Release() { return static_cast<T *>(Base::Release()); }
+    /**
+     * Releases the underlying buffer.
+     *
+     * The buffer stops being managed and will not be auto-freed.
+     */
+    CHECK_RETURN_VALUE T * Release() { return static_cast<T *>(Base::Release()); }
 
     ScopedMemoryBuffer & Calloc(size_t elementCount)
     {
@@ -222,7 +229,12 @@ class ScopedMemoryBufferWithSize : public ScopedMemoryBuffer<T>
         ScopedMemoryBuffer<T>::Free();
     }
 
-    T * Release()
+    /**
+     * Releases the underlying buffer.
+     *
+     * The buffer stops being managed and will not be auto-freed.
+     */
+    CHECK_RETURN_VALUE T * Release()
     {
         T * buffer = ScopedMemoryBuffer<T>::Release();
         mCount     = 0;