High level conclusions

Fuzzer commonmark_js is blocked:

The runtime code coverage of commonmark_js covers 29.41% 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 0.066% of cyclomatic complexity.

Fuzzers reach 0.057% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

1 / 1746

Cyclomatic complexity statically reachable by fuzzers

1 / 1499

Runtime code coverage of functions

246 / 1746

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: parse

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	806	41.7%
gold	[1:9]	2	0.10%
yellow	[10:29]	10	0.51%
greenyellow	[30:49]	3	0.15%
lawngreen	50+	1111	57.5%
All colors	1932	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
70	833	CodeDelims::find	call site: 00833	CodeDelims::find
70	919	delim_run_can_open	call site: 00919	CodeDelims::find
57	1069	delim_run_can_close	call site: 01069	scan_entity
48	236	FirstPass::parse_footnote	call site: 00236	InlineStack::push
37	366	scan_atx_heading	call site: 00366	FootnoteDefs::contains
37	1265	extract_attribute_block_content_from_header_text	call site: 01265	FootnoteDefs::contains
25	755	FirstPass::run	call site: 00755	Tree::append_text
25	799	Allocations::allocate_alignment	call site: 00799	delim_run_can_open
24	727	TreeIndex::add	call site: 00727	FirstPass::run
23	129	LineStart::is_at_eol	call site: 00129	FootnoteDefs::contains
23	1016	puncttable::is_punctuation	call site: 01016	is_punctuation
22	164	CodeDelims::insert	call site: 00164	CodeDelims::insert

Runtime coverage analysis

Covered functions

454

Functions that are reachable but not covered

1

Reachable functions

2

Percentage of reachable functions covered

50.0%

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.

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/parse.rs	2
pulldown-cmark/src/parse.rs	45
pulldown-cmark/src/firstpass.rs	228
pulldown-cmark/src/scanners.rs	94
dos-fuzzer/src/literals.rs	30
pulldown-cmark/src/tree.rs	18
dos-fuzzer/src/main.rs	1
pulldown-cmark/src/strings.rs	21
pulldown-cmark/src/lib.rs	1
pulldown-cmark/src/linklabel.rs	13
pulldown-cmark/tests/html.rs	5
pulldown-cmark/src/html.rs	5
pulldown-cmark/build.rs	8
pulldown-cmark/src/puncttable.rs	2
pulldown-cmark/src/cjk.rs	6
pulldown-cmark/src/entities.rs	3

Fuzzer: commonmark_js

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	1286	57.1%
gold	[1:9]	5	0.22%
yellow	[10:29]	4	0.17%
greenyellow	[30:49]	7	0.31%
lawngreen	50+	950	42.1%
All colors	2252	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
70	1007	delim_run_can_open	call site: 01007	CodeDelims::find
69	928	CodeDelims::find	call site: 00928	CodeDelims::find
57	1157	delim_run_can_close	call site: 01157	scan_entity
56	332	FirstPass::parse_block	call site: 00332	FirstPass::parse_footnote
47	1562	FirstPass::parse_block	call site: 01562	unescape
39	880	Tree::append	call site: 00880	delim_run_can_open
37	1296	FirstPass::parse_line	call site: 01296	FirstPass::parse_table
36	1370	HeadingIndex::get	call site: 01370	parse_inside_attribute_block
33	2023	pulldown_cmark_fuzz::commonmark_js	call site: 02023	get
25	850	FirstPass::run	call site: 00850	Tree::append_text
23	1104	puncttable::is_punctuation	call site: 01104	is_punctuation
22	1271	Tree::with_capacity	call site: 01271	delim_run_can_open

Runtime coverage analysis

Covered functions

638

Functions that are reachable but not covered

12

Reachable functions

17

Percentage of reachable functions covered

29.41%

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/commonmark_js.rs	14
pulldown-cmark/src/firstpass.rs	228
pulldown-cmark/src/parse.rs	45
dos-fuzzer/src/literals.rs	31
dos-fuzzer/src/main.rs	1
pulldown-cmark/src/strings.rs	21
fuzz/src/lib.rs	71
pulldown-cmark/src/tree.rs	18
pulldown-cmark/src/main.rs	2
pulldown-cmark/src/scanners.rs	94
pulldown-cmark/src/lib.rs	7
pulldown-cmark/src/linklabel.rs	13
pulldown-cmark/tests/html.rs	5
pulldown-cmark/src/html.rs	5
pulldown-cmark/build.rs	8
pulldown-cmark/src/puncttable.rs	2
pulldown-cmark/src/cjk.rs	6
pulldown-cmark/src/entities.rs	3
pulldown-cmark/tests/errors.rs	1

Fuzzer: html

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	794	41.0%
gold	[1:9]	2	0.10%
yellow	[10:29]	10	0.51%
greenyellow	[30:49]	3	0.15%
lawngreen	50+	1127	58.2%
All colors	1936	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
76	833	CodeDelims::find	call site: 00833	CodeDelims::find
70	919	delim_run_can_open	call site: 00919	CodeDelims::find
57	1069	delim_run_can_close	call site: 01069	scan_entity
48	236	FirstPass::parse_footnote	call site: 00236	InlineStack::push
25	755	FirstPass::run	call site: 00755	Tree::append_text
25	799	Allocations::allocate_alignment	call site: 00799	delim_run_can_open
23	1016	puncttable::is_punctuation	call site: 01016	is_punctuation
22	1183	Tree::with_capacity	call site: 01183	delim_run_can_open
21	1486	FirstPass::parse_block	call site: 01486	scan_entity
20	31	FootnoteDefs::contains	call site: 00031	special_bytes
20	164	CodeDelims::insert	call site: 00164	CodeDelims::insert
20	383	&[u8]::get	call site: 00383	CodeDelims::insert

Runtime coverage analysis

Covered functions

751

Functions that are reachable but not covered

2

Reachable functions

4

Percentage of reachable functions covered

50.0%

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.

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/html.rs	4
pulldown-cmark/src/parse.rs	45
pulldown-cmark/src/firstpass.rs	228
pulldown-cmark/src/scanners.rs	94
dos-fuzzer/src/literals.rs	30
pulldown-cmark/src/tree.rs	18
dos-fuzzer/src/main.rs	1
pulldown-cmark/src/strings.rs	21
pulldown-cmark/src/lib.rs	1
pulldown-cmark/src/linklabel.rs	13
pulldown-cmark/tests/html.rs	5
pulldown-cmark/src/html.rs	5
pulldown-cmark/build.rs	8
pulldown-cmark/src/puncttable.rs	2
pulldown-cmark/src/cjk.rs	6
pulldown-cmark/src/entities.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

1 / 1746

Cyclomatic complexity statically reachable by fuzzers

1 / 1499

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/parse.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=['CodeDelims::find', 'fuzz_target', 'delim_run_can_close', 'FirstPass::parse_footnote', 'scan_atx_heading', 'extract_attribute_block_content_from_header_text', 'FirstPass::run', 'Allocations::allocate_alignment', 'TreeIndex::add', 'LineStart::is_at_eol']

fuzz/fuzz_targets/commonmark_js.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=['delim_run_can_open', 'CodeDelims::find', 'delim_run_can_close', 'fuzz_target', 'Tree::append', 'HeadingIndex::get', 'pulldown_cmark_fuzz::commonmark_js', 'FirstPass::run']

fuzz/fuzz_targets/html.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=['CodeDelims::find', 'fuzz_target', 'delim_run_can_close', 'FirstPass::parse_footnote', 'FirstPass::run', 'Allocations::allocate_alignment', 'puncttable::is_punctuation', 'Tree::with_capacity', 'FootnoteDefs::contains']

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%
deflate	257	62	24.12%
inflate	612	299	48.85%
memchr::arch::generic::memchr::Threecore::core_arch::x86::__m128i::find_raw	63	21	33.33%
quick_xml::events::attributes::IterState::next	45	16	35.55%
quick_xml::reader::BangType::parse	32	9	28.12%
quick_xml::reader::parser::Parser::emit_bang	37	15	40.54%

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/pulldown-cmark/guide/demo/src/lib.rs	[]	[]
/src/pulldown-cmark/bench/benches/markdown-it.rs	[]	[]
/src/pulldown-cmark/dos-fuzzer/src/clock.rs	[]	[]
/src/pulldown-cmark/dos-fuzzer/src/scoring.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/parse.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/blockquotes_tags.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/spec.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/linklabel.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/serde.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/html.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/src/scanners.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/highlight.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/main.rs	['commonmark_js']	[]
/src/pulldown-cmark/fuzz/fuzz_targets/html.rs	['html']	[]
/src/pulldown-cmark/dos-fuzzer/src/literals.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/dos-fuzzer/src/main.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/heading_attrs.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/footnotes.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/container_extensions.rs	[]	[]
/src/pulldown-cmark/fuzz/fuzz_targets/commonmark_js.rs	['commonmark_js']	[]
/src/pulldown-cmark/pulldown-cmark/src/firstpass.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/src/cjk.rs	['parse', 'commonmark_js', 'html']	['parse', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/definition_lists.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/errors.rs	['commonmark_js']	['commonmark_js']
/src/pulldown-cmark/pulldown-cmark/tests/suite/table.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/gfm_table.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/regression.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark-escape/src/lib.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/gfm_tasklist.rs	[]	[]
/src/pulldown-cmark/bench/benches/lib.rs	[]	[]
/src/pulldown-cmark/fuzz/src/lib.rs	['commonmark_js']	['commonmark_js']
/src/pulldown-cmark/pulldown-cmark/tests/lib.rs	[]	[]
/src/pulldown-cmark/guide/prepare-specs.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/smart_punct.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/super_sub.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/build.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/src/strings.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/bench/benches/html_rendering.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/utils.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/cjk_friendly_emphasis.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/entities.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/strikethrough.rs	[]	[]
/src/pulldown-cmark/fuzz/fuzz_targets/parse.rs	['parse']	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/gfm_strikethrough.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/wikilinks.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/puncttable.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/old_footnotes.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/examples/normalize-wikilink.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/lib.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/suite/math.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/tests/suite/metadata_blocks.rs	[]	[]
/src/pulldown-cmark/dos-fuzzer/src/black_box.rs	[]	[]
/src/pulldown-cmark/pulldown-cmark/src/tree.rs	['parse', 'commonmark_js', 'html']	['parse', 'commonmark_js', 'html']
/src/pulldown-cmark/pulldown-cmark/tests/html.rs	['parse', 'commonmark_js', 'html']	[]

Directories in report

Directory
/src/pulldown-cmark/guide/demo/src/
/src/pulldown-cmark/pulldown-cmark/src/
/src/pulldown-cmark/pulldown-cmark/tests/
/src/pulldown-cmark/pulldown-cmark/tests/suite/
/src/pulldown-cmark/dos-fuzzer/src/
/src/pulldown-cmark/fuzz/fuzz_targets/
/src/pulldown-cmark/pulldown-cmark-escape/src/
/src/pulldown-cmark/pulldown-cmark/
/src/pulldown-cmark/guide/
/src/pulldown-cmark/fuzz/src/
/src/pulldown-cmark/bench/benches/
/src/pulldown-cmark/pulldown-cmark/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