Use-of-uninitialized-value bug in boost/property_tree/detail/xml_parser_read_rapidxml.hpp:96:9 in void boost::property_tree::xml_parser::read_xml_internal

More detail is depicted in [bugdetail](https://github.com/fceval/romefuzz-appendix/tree/e7d003eaf202552523e244413a6bf661d257dc2a/realbugs/boost).

==2619035==WARNING: MemorySanitizer: use-of-uninitialized-value
FUNCTIONSTARTvoid boost::property_tree::xml_parser::read_xml_internal, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > > >(std::basic_istream, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type::value_type, std::char_traits, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type> >&, boost::property_tree::basic_ptree, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >&, int, std::__cxx11::basic_string, std::allocator > const&)FUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/./boost/property_tree/detail/xml_parser_read_rapidxml.hpp:96:9LOCATIONEND----FRAMESTART0FRAMEEND
FUNCTIONSTARTvoid boost::property_tree::xml_parser::read_xml, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > > >(std::basic_istream, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type::value_type, std::char_traits, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type> >&, boost::property_tree::basic_ptree, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >&, int)FUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/./boost/property_tree/xml_parser.hpp:52:9LOCATIONEND----FRAMESTART1FRAMEEND
FUNCTIONSTART(anonymous namespace)::graphml_reader::run(std::istream&, unsigned long)FUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/libs/graph/src/graphml.cpp:81:9LOCATIONEND----FRAMESTART2FRAMEEND
FUNCTIONSTARTboost::read_graphml(std::istream&, boost::mutate_graph&, unsigned long)FUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/libs/graph/src/graphml.cpp:309:12LOCATIONEND----FRAMESTART3FRAMEEND
FUNCTIONSTARTvoid boost::read_graphml, std::allocator >, boost::no_property>, boost::property, boost::no_property, boost::listS> >(std::istream&, boost::adjacency_list, std::allocator >, boost::no_property>, boost::property, boost::no_property, boost::listS>&, boost::dynamic_properties&, unsigned long)FUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/./boost/graph/graphml.hpp:233:5LOCATIONEND----FRAMESTART4FRAMEEND
FUNCTIONSTARTLLVMFuzzerTestOneInputFUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/boost_graph_graphml_fuzzer.cc:39:9LOCATIONEND----FRAMESTART5FRAMEEND
FUNCTIONSTARTmainFUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/standaloneengine.cc:50:11LOCATIONEND----FRAMESTART6FRAMEEND
FUNCTIONSTART__libc_start_mainFUNCTIONEND----LOCATIONSTART/build/glibc-B3wQXB/glibc-2.31/csu/../csu/libc-start.c:308:16LOCATIONEND----FRAMESTART7FRAMEEND
FUNCTIONSTART_startFUNCTIONEND----LOCATIONSTARTLOCATIONEND----FRAMESTART8FRAMEEND

Uninitialized value was created by an allocation of 'input' in the stack frame of function 'LLVMFuzzerTestOneInput'
FUNCTIONSTARTLLVMFuzzerTestOneInputFUNCTIONEND----LOCATIONSTARTout_boost/CRASHMSAN/repo/boost_graph_graphml_fuzzer.cc:32LOCATIONEND----FRAMESTART0FRAMEEND

SUMMARY: MemorySanitizer: use-of-uninitialized-value out_boost/CRASHMSAN/repo/./boost/property_tree/detail/xml_parser_read_rapidxml.hpp:96:9 in void boost::property_tree::xml_parser::read_xml_internal, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > > >(std::basic_istream, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type::value_type, std::char_traits, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >::key_type> >&, boost::property_tree::basic_ptree, std::allocator >, std::__cxx11::basic_string, std::allocator >, std::less, std::allocator > > >&, int, std::__cxx11::basic_string, std::allocator > const&)
Exiting