Lagom/Fuzzers: Add fuzzer for the LibCrypto PEM parser

Author: https://github.com/bgianfo
Commit: https://github.com/SerenityOS/serenity/commit/aa118642aaf
Pull-request: https://github.com/SerenityOS/serenity/pull/10108
Reviewed-by: https://github.com/alimpfard

Meta/Lagom/Fuzzers/CMakeLists.txt

@@ -28,6 +28,7 @@ add_simple_fuzzer(FuzzGzipDecompression LagomCompress)
 add_simple_fuzzer(FuzzICOLoader LagomGfx)
 add_simple_fuzzer(FuzzJPGLoader LagomGfx)
 add_simple_fuzzer(FuzzMD5 LagomCrypto)
+add_simple_fuzzer(FuzzPEM LagomCrypto)
 add_simple_fuzzer(FuzzPNGLoader LagomGfx)
 add_simple_fuzzer(FuzzPBMLoader LagomGfx)
 add_simple_fuzzer(FuzzPGMLoader LagomGfx)

Meta/Lagom/Fuzzers/FuzzPEM.cpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Brian Gianforcaro <bgianf@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCrypto/ASN1/PEM.h>
+#include <stddef.h>
+#include <stdint.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+    (void)Crypto::decode_pem({ data, size });
+    return 0;
+}