Random fixes (dotnet#853)

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Array.CoreRT.cs

@@ -125,6 +125,14 @@ public static Array CreateInstance(Type elementType, params int[] lengths)
             if (lengths.Length == 0)
                 throw new ArgumentException(SR.Arg_NeedAtLeast1Rank);
 
+            // Check to make sure the lengths are all positive. Note that we check this here to give
+            // a good exception message if they are not; however we check this again inside the execution
+            // engine's low level allocation function after having made a copy of the array to prevent a
+            // malicious caller from mutating the array after this check.
+            for (int i = 0; i < lengths.Length; i++)
+                if (lengths[i] < 0)
+                    ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.lengths, i, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
+
             if (lengths.Length == 1)
             {
                 int length = lengths[0];

src/coreclr/nativeaot/System.Private.CoreLib/src/System/InvokeUtils.cs

@@ -319,7 +319,7 @@ private static object GetDefaultValue(object targetMethodOrDelegate, RuntimeType
             bool hasDefaultValue = RuntimeAugments.Callbacks.TryGetDefaultParameterValue(targetMethodOrDelegate, thType, argIndex, out object defaultValue);
             if (!hasDefaultValue)
             {
-                throw new ArgumentException(SR.Arg_DefaultValueMissingException);
+                throw new ArgumentException(SR.Arg_DefaultValueMissingException, "parameters");
             }
 
             // Note that we might return null even for value types which cannot have null value here.

src/libraries/Common/tests/Tests/System/StringTests.cs

@@ -7263,6 +7263,7 @@ public static unsafe void CopyTest()
         }
 
         [Fact]
+        [ActiveIssue("https://github.com/dotnet/runtimelab/issues/823" /* NativeAot */)]
         public static unsafe void InternTest()
         {
             AssertExtensions.Throws<ArgumentNullException>("str", () => string.Intern(null));