Merge branch 'v0.38.4-aurora-branch' of github.com:aurora-is-near/spu…

…tnikvm into feat/merge-upstream

runtime/src/eval/system.rs

@@ -148,18 +148,20 @@ pub fn returndatacopy<H: Handler>(runtime: &mut Runtime) -> Control<H> {
 	pop_u256!(runtime, data_offset);
 	pop_usize!(runtime, len);
 
-	// If `len` is zero then nothing happens, regardless of the
-	// value of the other parameters. In particular, `memory_offset`
-	// might be larger than `usize::MAX`, hence why we check this first.
-	if len == 0 {
-		return Control::Continue;
-	}
-
-	// SAFETY: this cast is safe because if `len > 0` then gas cost of memory
-	// would have already been taken into account at this point. It is impossible
-	// to have a memory offset greater than `usize::MAX` for any gas limit less
-	// than `u64::MAX` (and gas limits higher than this are disallowed in general).
-	let memory_offset = memory_offset.as_usize();
+	// If `len` is zero then nothing happens to the memory, regardless
+	// of the value of `memory_offset`. In particular, the value taken
+	// from the stack might be larger than `usize::MAX`, hence why the
+	// `as_usize` cast is not always safe. But because the value does
+	// not matter when `len == 0` we can safely set it equal to zero instead.
+	let memory_offset = if len == 0 {
+		0
+	} else {
+		// SAFETY: this cast is safe because if `len > 0` then gas cost of memory
+		// would have already been taken into account at this point. It is impossible
+		// to have a memory offset greater than `usize::MAX` for any gas limit less
+		// than `u64::MAX` (and gas limits higher than this are disallowed in general).
+		memory_offset.as_usize()
+	};
 
 	try_or_fail!(runtime
 		.machine