Fuzzers: Add a fuzzer for JsonParser

Author: https://github.com/tcl3
Commit: https://github.com/SerenityOS/serenity/commit/03fbd6c0c8
Pull-request: https://github.com/SerenityOS/serenity/pull/21544

Meta/Lagom/Fuzzers/FuzzJsonParser.cpp

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2023, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonParser.h>
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
+{
+    JsonParser parser({ data, size });
+    (void)parser.parse();
+    return 0;
+}

Meta/Lagom/Fuzzers/fuzzers.cmake

@@ -21,6 +21,7 @@ set(FUZZER_TARGETS
     IMAPParser
     JPEGLoader
     Js
+    JsonParser
     Latin1Decoder
     Latin2Decoder
     LzmaDecompression

Userland/Utilities/test-fuzz.cpp

@@ -35,6 +35,7 @@
     T(IMAPParser)            \
     T(JPEGLoader)            \
     T(Js)                    \
+    T(JsonParser)            \
     T(Latin1Decoder)         \
     T(Latin2Decoder)         \
     T(LzmaDecompression)     \