From eb83ebf1bd98f77e877539b05d07ffcfddb87f6f Mon Sep 17 00:00:00 2001
From: Bhargava Shastry <bhargava.shastry@ethereum.org>
Date: Wed, 5 May 2021 22:08:25 +0200
Subject: [PATCH] Do not apply mutation if it is too large.

---
 .../tools/ossfuzz/SolidityCustomMutatorInterface.cpp | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/test/tools/ossfuzz/SolidityCustomMutatorInterface.cpp b/test/tools/ossfuzz/SolidityCustomMutatorInterface.cpp
index fad3f08a4..11814574a 100644
--- a/test/tools/ossfuzz/SolidityCustomMutatorInterface.cpp
+++ b/test/tools/ossfuzz/SolidityCustomMutatorInterface.cpp
@@ -64,7 +64,13 @@ size_t SolidityCustomMutatorInterface::generate()
 		data,
 		"Solc custom mutator: Invalid mutant or memory pointer"
 	);
-	size_t mutantSize = min(testCase.size(), maxMutantSize - 1);
-	mempcpy(data, testCase.data(), mutantSize);
-	return mutantSize;
+	// Do not apply the mutation if mutant is greater in size than maximum
+	// permissible. libFuzzer's default max permissible is around 4 KB.
+	if (testCase.size() > (maxMutantSize - 1))
+		return size;
+	else
+	{
+		mempcpy(data, testCase.data(), testCase.size());
+		return testCase.size();
+	}
 }