UnBoxEachElement only allows exact type match

dotnet · Jan 24, 2024 · 491dd2e · 491dd2e
1 parent 79ff323
commit 491dd2e
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Showing 2 changed files with 5 additions and 4 deletions.
diff --git a/src/coreclr/System.Private.CoreLib/src/System/Array.CoreCLR.cs b/src/coreclr/System.Private.CoreLib/src/System/Array.CoreCLR.cs
@@ -176,22 +176,23 @@ private static unsafe void CopyImplUnBoxEachElement(Array sourceArray, int sourc
                         pDestMT,
                         obj);
                 }
-                else if (obj is null)
+                else if (obj is null || RuntimeHelpers.GetMethodTable(obj) != pDestMT)
                 {
+                    GC.KeepAlive(obj);
                     ThrowHelper.ThrowInvalidCastException_DownCastArrayElement();
                 }
                 else if (pDestMT->ContainsGCPointers)
                 {
                     Buffer.BulkMoveWithWriteBarrier(
                         ref dest,
-                        ref CastHelpers.Unbox(pDestMT, obj),
+                        ref obj.GetRawData(),
                         destSize);
                 }
                 else
                 {
                     Buffer.Memmove(
                         ref dest,
-                        ref CastHelpers.Unbox(pDestMT, obj),
+                        ref obj.GetRawData(),
                         destSize);
                 }
             }

diff --git a/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/CastHelpers.cs b/src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/CastHelpers.cs
@@ -389,7 +389,7 @@ internal static unsafe class CastHelpers
         [DebuggerHidden]
         [StackTraceHidden]
         [DebuggerStepThrough]
-        internal static ref byte Unbox(void* toTypeHnd, object obj)
+        private static ref byte Unbox(void* toTypeHnd, object obj)
         {
             // this will throw NullReferenceException if obj is null, attributed to the user code, as expected.
             if (RuntimeHelpers.GetMethodTable(obj) == toTypeHnd)