Meta: Add fuzzer for Poly1305

Author: https://github.com/stelar7
Commit: https://github.com/SerenityOS/serenity/commit/ce08fae13b
Pull-request: https://github.com/SerenityOS/serenity/pull/13549
Reviewed-by: https://github.com/alimpfard

Meta/Lagom/Fuzzers/CMakeLists.txt

@@ -36,6 +36,7 @@ add_simple_fuzzer(FuzzPEM LagomCrypto)
 add_simple_fuzzer(FuzzPNGLoader LagomGfx)
 add_simple_fuzzer(FuzzPBMLoader LagomGfx)
 add_simple_fuzzer(FuzzPGMLoader LagomGfx)
+add_simple_fuzzer(FuzzPoly1305 LagomCrypto)
 add_simple_fuzzer(FuzzPPMLoader LagomGfx)
 add_simple_fuzzer(FuzzPDF LagomPDF)
 add_simple_fuzzer(FuzzQOILoader LagomGfx)

Meta/Lagom/Fuzzers/FuzzPoly1305.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2022, stelar7 <dudedbz@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCrypto/Authentication/Poly1305.h>
+#include <stddef.h>
+#include <stdint.h>
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
+{
+    if (size < 32)
+        return 0;
+
+    auto initial = ReadonlyBytes { data, 32 };
+    auto message = ReadonlyBytes { data + 32, size - 32 };
+
+    Crypto::Authentication::Poly1305 mac(initial);
+    mac.update(message);
+    (void)mac.digest();
+    return 0;
+}