High level conclusions

Fuzzer fuzz_chunked_reader is blocked:

The runtime code coverage of fuzz_chunked_reader covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzers reach 4.577% of cyclomatic complexity.

Fuzzers reach 1.762% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

26 / 1475

Cyclomatic complexity statically reachable by fuzzers

72 / 1573

Runtime code coverage of functions

391 / 1475

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: fuzz_chunked_reader

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	338	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	338	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
337	0	EP	call site: 00000	NsReader::read_resolved_event

Runtime coverage analysis

Covered functions

2

Functions that are reachable but not covered

56

Reachable functions

56

Percentage of reachable functions covered

0.0%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
fuzz/fuzz_targets/fuzz_chunked_reader.rs	14
src/reader/ns_reader.rs	32
src/lib.rs	3
src/encoding.rs	18
src/name.rs	43
src/se/mod.rs	2
src/utils.rs	1
src/events/mod.rs	7
tests/reader-namespaces.rs	5
tests/serde_helpers/mod.rs	5
src/events/attributes.rs	5
tests/encodings.rs	6
tests/serde-de-enum.rs	16
tests/escape.rs	19
src/escape.rs	3
src/writer.rs	3

Fuzzer: structured_roundtrip

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	364	70.9%
gold	[1:9]	6	1.16%
yellow	[10:29]	3	0.58%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	140	27.2%
All colors	513	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
74	153	NamespaceResolver::set_level	call site: 00153	NsReader::read_resolved_event
49	242	NamespaceResolver::pop	call site: 00242	read_event_impl
23	93	fuzz_round_trip	call site: 00093	SpecIter::next
21	21	fuzz_round_trip	call site: 00021	Writer::write_wrapped
21	47	Writer::write_wrapped	call site: 00047	Writer::write_wrapped
21	299	NsReader::process_event	call site: 00299	NsReader::read_event
19	413	ElementWriter::write_text_content	call site: 00413	Writer::write_wrapped
15	440	ElementWriter::write_text_content	call site: 00440	read_to_end
14	78	fuzz_round_trip	call site: 00078	Decoder::decode_into
11	121	NamespaceResolver::push	call site: 00121
11	228	NamespaceResolver::set_level	call site: 00228
11	373	BytesStart::push_attr	call site: 00373	Decoder::decode_into

Runtime coverage analysis

Covered functions

348

Functions that are reachable but not covered

28

Reachable functions

62

Percentage of reachable functions covered

54.84%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
fuzz/fuzz_targets/structured_roundtrip.rs	30
src/encoding.rs	20
src/se/mod.rs	2
src/utils.rs	2
src/writer.rs	37
tests/roundtrip.rs	1
src/events/mod.rs	20
tests/html.rs	11
src/name.rs	43
tests/serde-de-enum.rs	16
tests/serde_helpers/mod.rs	5
src/reader/ns_reader.rs	38
src/lib.rs	3
tests/reader-namespaces.rs	5
src/events/attributes.rs	5
tests/encodings.rs	6

Fuzzer: fuzz_target_1

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	645	90.4%
gold	[1:9]	0	0.0%
yellow	[10:29]	2	0.28%
greenyellow	[30:49]	2	0.28%
lawngreen	50+	64	8.97%
All colors	713	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
182	468	parse_number	call site: 00468	NsReader::read_event_into
110	109	QName::prefix	call site: 00109	NsReader::read_event
105	319	from_str_radix	call site: 00319	NamespaceResolver::push
49	238	QName::as_namespace_binding	call site: 00238	Attribute::normalized_value
41	11	Reader::from_reader	call site: 00011	round_trip
28	54	Reader::from_str	call site: 00054	NsReader::read_resolved_event
27	288	Attribute::normalized_value	call site: 00288	normalize_attribute_value
23	85	QName::prefix	call site: 00085	NsReader::read_event_into
22	429	Writer::write_wrapped	call site: 00429	Writer::write_wrapped
20	654	BytesDecl::version	call site: 00654
17	695	BytesDecl::xml_version	call site: 00695	round_trip
10	0	EP	call site: 00000

Runtime coverage analysis

Covered functions

296

Functions that are reachable but not covered

44

Reachable functions

75

Percentage of reachable functions covered

41.33%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
fuzz/fuzz_targets/fuzz_target_1.rs	28
src/encoding.rs	23
src/reader/ns_reader.rs	32
src/lib.rs	3
src/name.rs	43
src/se/mod.rs	5
src/utils.rs	1
src/events/mod.rs	23
tests/reader-namespaces.rs	5
tests/serde_helpers/mod.rs	5
src/events/attributes.rs	14
tests/encodings.rs	8
tests/serde-de-enum.rs	16
tests/reader-dtd.rs	1
src/escape.rs	34
tests/writer-indentation.rs	7
src/writer.rs	34
tests/roundtrip.rs	1
tests/html.rs	11
tests/escape.rs	19
tests/writer.rs	20
tests/reader.rs	3

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers

26 / 1475

Cyclomatic complexity statically reachable by fuzzers

72 / 1573

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

fuzz/fuzz_targets/fuzz_chunked_reader.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

fuzz/fuzz_targets/structured_roundtrip.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['NamespaceResolver::set_level', 'NamespaceResolver::pop', 'fuzz_round_trip', 'Writer::write_wrapped', 'NsReader::process_event', 'ElementWriter::write_text_content', 'NamespaceResolver::push']

fuzz/fuzz_targets/fuzz_target_1.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['parse_number', 'QName::prefix', 'from_str_radix', 'QName::as_namespace_binding', 'Reader::from_reader', 'Reader::from_str', 'Attribute::normalized_value', 'Writer::write_wrapped', 'BytesDecl::version']

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name	Function total lines	Lines covered at runtime	percentage covered	Reached by fuzzers
memchr::arch::generic::memchr::Onecore::core_arch::x86::__m128i::find_raw	63	30	47.61%
memchr::arch::generic::memchr::Threecore::core_arch::x86::__m128i::find_raw	63	30	47.61%

New fuzzers

The below fuzzers are templates and suggestions for how to target the set of optimal functions above

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file	Reached by	Covered by
/src/quick-xml/src/de/mod.rs	[]	[]
/src/quick-xml/src/reader/state.rs	[]	[]
/src/quick-xml/fuzz/fuzz_targets/fuzz_target_1.rs	['fuzz_target_1']	[]
/src/quick-xml/src/reader/buffered_reader.rs	[]	[]
/src/quick-xml/src/de/resolver.rs	[]	[]
/src/quick-xml/src/encoding.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/de/attributes.rs	[]	[]
/src/quick-xml/src/de/simple_type.rs	[]	[]
/src/quick-xml/tests/writer-indentation.rs	['fuzz_target_1']	[]
/src/quick-xml/src/utils.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/reader/mod.rs	[]	[]
/src/quick-xml/tests/serde-de-xsi.rs	[]	[]
/src/quick-xml/src/errors.rs	[]	[]
/src/quick-xml/tests/issues.rs	[]	[]
/src/quick-xml/src/name.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/parser/pi.rs	[]	[]
/src/quick-xml/tests/fuzzing.rs	[]	[]
/src/quick-xml/tests/reader.rs	['fuzz_target_1']	['fuzz_target_1']
/src/quick-xml/src/escape.rs	['fuzz_chunked_reader', 'fuzz_target_1']	['fuzz_target_1']
/src/quick-xml/tests/async-tokio.rs	[]	[]
/src/quick-xml/src/events/mod.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/reader/ns_reader.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/se/simple_type.rs	[]	[]
/src/quick-xml/src/reader/slice_reader.rs	[]	[]
/src/quick-xml/tests/reader-attributes.rs	[]	[]
/src/quick-xml/tests/escape.rs	['fuzz_chunked_reader', 'fuzz_target_1']	[]
/src/quick-xml/src/serde_helpers.rs	[]	[]
/src/quick-xml/benches/macrobenches.rs	[]	[]
/src/quick-xml/tests/encodings.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	[]
/src/quick-xml/src/de/map.rs	[]	[]
/src/quick-xml/examples/read_texts.rs	[]	[]
/src/quick-xml/test-gen/src/main.rs	[]	[]
/src/quick-xml/tests/serde-de-enum.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/compare/benches/serde.rs	[]	[]
/src/quick-xml/fuzz/fuzz_targets/structured_roundtrip.rs	['structured_roundtrip']	['structured_roundtrip']
/src/quick-xml/benches/microbenches.rs	[]	[]
/src/quick-xml/compare/benches/low-level.rs	[]	[]
/src/quick-xml/src/lib.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/fuzz/fuzz_targets/fuzz_chunked_reader.rs	['fuzz_chunked_reader']	[]
/src/quick-xml/examples/custom_entities.rs	[]	[]
/src/quick-xml/src/de/var.rs	[]	[]
/src/quick-xml/tests/reader-config.rs	[]	[]
/src/quick-xml/tests/helpers/mod.rs	[]	[]
/src/quick-xml/src/de/text.rs	[]	[]
/src/quick-xml/src/se/key.rs	[]	[]
/src/quick-xml/src/parser/element.rs	[]	[]
/src/quick-xml/src/de/key.rs	[]	[]
/src/quick-xml/src/parser/dtd.rs	[]	[]
/src/quick-xml/tests/writer.rs	['fuzz_target_1']	['fuzz_target_1']
/src/quick-xml/src/parser/comment.rs	[]	[]
/src/quick-xml/tests/serde-de-seq.rs	[]	[]
/src/quick-xml/examples/flattened_enum.rs	[]	[]
/src/quick-xml/examples/read_nodes.rs	[]	[]
/src/quick-xml/tests/reader-dtd.rs	['fuzz_target_1']	[]
/src/quick-xml/tests/reader-errors.rs	[]	[]
/src/quick-xml/tests/reader-read-text.rs	[]	[]
/src/quick-xml/src/writer.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/se/text.rs	[]	[]
/src/quick-xml/tests/roundtrip.rs	['structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/se/content.rs	[]	[]
/src/quick-xml/tests/html.rs	['structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/se/element.rs	[]	[]
/src/quick-xml/tests/serde-de.rs	[]	[]
/src/quick-xml/src/reader/async_tokio.rs	[]	[]
/src/quick-xml/src/se/mod.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/src/writer/async_tokio.rs	[]	[]
/src/quick-xml/src/events/attributes.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/tests/reader-namespaces.rs	['fuzz_chunked_reader', 'structured_roundtrip', 'fuzz_target_1']	['structured_roundtrip', 'fuzz_target_1']
/src/quick-xml/tests/serde-issues.rs	[]	[]
/src/quick-xml/tests/reader-references.rs	[]	[]
/src/quick-xml/benches/encoding.rs	[]	[]

Directories in report

Directory
/src/quick-xml/compare/benches/
/src/quick-xml/benches/
/src/quick-xml/test-gen/src/
/src/quick-xml/src/
/src/quick-xml/fuzz/fuzz_targets/
/src/quick-xml/src/parser/
/src/quick-xml/src/reader/
/src/quick-xml/src/writer/
/src/quick-xml/src/se/
/src/quick-xml/src/de/
/src/quick-xml/src/events/
/src/quick-xml/tests/helpers/
/src/quick-xml/tests/
/src/quick-xml/examples/

This section shows a list of 3rd party function calls and their relative coverage information. By static analysis of the target project code, all of the 3rd party function call and their caller information, including the source file and line number that initiate the call are captured. The caller source code file and line number are shown in column 2 while column 1 is the function name of the 3rd party function call. Each occurrent of the 3rd party function call will occuply a separate row. Column 3 of each row indicate if the 3rd party call in the source file line is unreachable. Column 4 lists all fuzzers that have covered that particular system call in that specific location (source file and line)during their dynamic fuzzing.

Function in each files in report

Target sink	Callsite location	Reached by fuzzer	Covered by Fuzzers