[idl_parser] Unify parsing of NaN values read from .fbs and .json files (#6296)

This commit unifies parsing of NaN values read
from .fbs and .json files by converting them to unsigned NaN.

tests/fuzzer/CMakeLists.txt

@@ -139,6 +139,23 @@ target_link_libraries(monster_fuzzer PRIVATE flatbuffers_fuzzed)
 # Build debugger for weird cases found with fuzzer.
 if(BUILD_DEBUGGER)
   add_library(flatbuffers_nonfuzz STATIC ${FlatBuffers_Library_SRCS})
+  target_compile_options(
+    flatbuffers_nonfuzz
+    PUBLIC
+      $<$<BOOL:${USE_ASAN}>:
+        -fsanitize=undefined,address
+      >
+      -fno-limit-debug-info
+  )
+  
+  target_link_libraries(
+    flatbuffers_nonfuzz
+    PUBLIC
+      $<$<BOOL:${USE_ASAN}>:
+        -fsanitize=undefined,address
+      >
+  )
+
   target_compile_definitions(
     flatbuffers_nonfuzz
     PUBLIC
@@ -147,6 +164,9 @@ if(BUILD_DEBUGGER)
     PRIVATE
       FLATBUFFERS_MAX_PARSING_DEPTH=${FLATBUFFERS_MAX_PARSING_DEPTH}
   )
-  add_executable(scalar_debug flatbuffers_scalar_fuzzer.cc scalar_debug.cpp)
+  add_executable(scalar_debug
+    flatbuffers_scalar_fuzzer.cc
+    scalar_debug.cpp
+  )
   target_link_libraries(scalar_debug PRIVATE flatbuffers_nonfuzz)
 endif(BUILD_DEBUGGER)

tests/fuzzer/flatbuffers_scalar_fuzzer.cc

@@ -288,7 +288,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     }
 
     // Parse original input as-is.
-    auto orig_scalar = "{ \"Y\" : " + input + " }";
+    auto orig_scalar = "{\"Y\" : " + input + "}";
     std::string orig_back;
     auto orig_done = Parse(parser, orig_scalar, &orig_back);
 
@@ -326,7 +326,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 
     // Test quoted version of the string
     if (!qouted_input.empty()) {
-      auto fix_scalar = "{ \"Y\" : " + qouted_input + " }";
+      auto fix_scalar = "{\"Y\" : " + qouted_input + "}";
       std::string fix_back;
       auto fix_done = Parse(parser, fix_scalar, &fix_back);
 

tests/fuzzer/scalar_debug.cpp

@@ -23,6 +23,6 @@ int main(int argc, char *argv[]) {
   auto rc = LLVMFuzzerTestOneInput(
       reinterpret_cast<const uint8_t *>(crash_file_data.data()),
       crash_file_data.size());
-  std::cout << "LLVMFuzzerTestOneInput finished with code " << rc;
+  std::cout << "LLVMFuzzerTestOneInput finished with code " << rc << "\n\n";
   return rc;
 }

tests/fuzzer/scalar_json.dict

@@ -17,7 +17,11 @@
 "e"
 "f"
 "nan"
+"-nan"
+"+nan"
 "inf"
+"+inf"
 "-inf"
 "infinity"
+"+infinity"
 "-infinity"