High level conclusions

Fuzzers reach 69.31% code coverage.

Fuzzer parso_fuzz is blocked:

The runtime code coverage of parso_fuzz covers 23.80% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer parso_extended_fuzz is blocked:

The runtime code coverage of parso_extended_fuzz covers 23.07% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer parso_pep8_fuzz is blocked:

The runtime code coverage of parso_pep8_fuzz covers 21.73% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Reachability and coverage overview

Functions statically reachable by fuzzers

46 / 440

Cyclomatic complexity statically reachable by fuzzers

170 / 1598

Runtime code coverage of functions

305 / 440

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	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: parso_pep8_fuzz

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	0	0.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	26	100.%
All colors	26	100

Runtime coverage analysis

Covered functions

330

Functions that are reachable but not covered

18

Reachable functions

23

Percentage of reachable functions covered

21.74%

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
/	1
...parso_pep8_fuzz	5
parso	3
parso.grammar	8
parso.utils	6

Fuzzer: parso_diff_fuzz

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	103	54.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	85	45.2%
All colors	188	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
38	88	parso.python.diff.DiffParser._parse	call site: 00088	parso.python.diff._NodesTree._copy_nodes
24	162	parso.python.diff._get_previous_leaf_if_indentation	call site: 00162	parso.python.diff._assert_valid_graph
14	50	parso.python.diff.DiffParser._diff_tokenize	call site: 00050	parso.python.diff._suite_or_file_input_is_valid
4	134	parso.utils.split_lines	call site: 00134	parso.python.diff.DiffParser._parse
4	144	parso.python.diff._get_next_leaf_if_indentation	call site: 00144	parso.python.diff._update_positions
3	36	parso.python.diff.DiffParser.update	call site: 00036	parso.python.diff.DiffParser._copy_from_old_parser
3	44	parso.python.diff._ends_with_newline	call site: 00044	parso.python.diff.DiffParser._parse
3	80	parso.python.diff._NodesTree.add_parsed_nodes	call site: 00080	parso.python.diff._NodesTreeNode.add_tree_nodes
3	158	parso.python.diff._NodesTree.close	call site: 00158	parso.python.diff._assert_valid_graph
2	40	parso.python.diff._ends_with_newline	call site: 00040	leaf.get_previous_leaf
2	154	parso.python.diff._NodesTree.close	call site: 00154	.len
1	84	parso.python.diff._NodesTreeNode.add_tree_nodes	call site: 00084	parso.python.diff._NodesTree._update_parsed_node_tos

Runtime coverage analysis

Covered functions

331

Functions that are reachable but not covered

74

Reachable functions

108

Percentage of reachable functions covered

31.48%

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
/	1
...parso_diff_fuzz	6
parso	3
parso.grammar	8
parso.utils	13
parso.python.diff	77
parso.python.parser	3

Fuzzer: parso_extended_fuzz

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	4	10.5%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	34	89.4%
All colors	38	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
2	31	...parso_extended_fuzz.fuzz_errors	call site: 00031	...parso_extended_fuzz.fuzz_errors
1	25	...parso_extended_fuzz.fuzz_dump	call site: 00025	...parso_extended_fuzz.fuzz_errors
1	36	...parso_extended_fuzz.TestOneInput	call site: 00036	...parso_extended_fuzz.fuzz_errors

Runtime coverage analysis

Covered functions

331

Functions that are reachable but not covered

20

Reachable functions

26

Percentage of reachable functions covered

23.08%

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
/	1
...parso_extended_fuzz	9
parso	3
parso.grammar	8
parso.utils	6

Fuzzer: parso_fuzz

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	0	0.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	24	100.%
All colors	24	100

Runtime coverage analysis

Covered functions

330

Functions that are reachable but not covered

16

Reachable functions

21

Percentage of reachable functions covered

23.81%

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
/	1
...parso_fuzz	3
parso	3
parso.grammar	8
parso.utils	6

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
parso.pgen2.generator.generate_grammar	parso.pgen2.generator	2	['N/A', 'N/A']	6	0	3	2	4	120	1	400	336
parso.grammar.Grammar.parse	parso.grammar	9	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	4	0	3	14	9	67	0	220	160
parso.python.pep8.PEP8Normalizer.visit_leaf	parso.python.pep8	2	['N/A', 'N/A']	4	0	5	5	5	33	1	148	121
parso.python.errors._NamedExprRule.is_issue	parso.python.errors	2	['N/A', 'N/A']	9	0	4	4	5	16	0	81	69
parso.python.parser.Parser.error_recovery	parso.python.parser	2	['N/A', 'N/A']	6	0	4	8	6	24	3	83	65
parso.python.pep8.PEP8Normalizer._visit_node	parso.python.pep8	2	['N/A', 'N/A']	2	0	7	27	14	19	8	73	44
parso.python.errors._get_rhs_name	parso.python.errors	2	['N/A', 'N/A']	2	0	0	33	16	5	2	46	35

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

Functions statically reachable by fuzzers

149 / 440

Cyclomatic complexity statically reachable by fuzzers

628 / 1598

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	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.

/src/parso_pep8_fuzz.py

Dictionary

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

/src/parso_diff_fuzz.py

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=['parso.python.diff.DiffParser._parse', 'parso.python.diff._get_previous_leaf_if_indentation', 'parso.python.diff.DiffParser._diff_tokenize', 'parso.utils.split_lines', 'parso.python.diff._get_next_leaf_if_indentation', 'parso.python.diff.DiffParser.update', 'parso.python.diff._ends_with_newline', 'parso.python.diff._NodesTree.add_parsed_nodes', 'parso.python.diff._NodesTree.close']

/src/parso_extended_fuzz.py

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=['...parso_extended_fuzz.fuzz_errors', '...parso_extended_fuzz.fuzz_dump', '...parso_extended_fuzz.TestOneInput']

/src/parso_fuzz.py

Dictionary

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

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
parso.grammar.Grammar.parse	42	19	45.23%	[]
parso.python.diff.DiffParser._diff_tokenize	37	16	43.24%	['parso_diff_fuzz']
parso.python.diff._NodesTree._copy_nodes	84	0	0.0%	['parso_diff_fuzz']

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
	[]	[]
parso.python.errors	[]	[]
parso.file_io	[]	[]
parso.parser	[]	[]
...parso_extended_fuzz	['parso_extended_fuzz']	[]
platform	[]	[]
parso	['parso_pep8_fuzz', 'parso_diff_fuzz', 'parso_extended_fuzz', 'parso_fuzz']	[]
hashlib	[]	[]
	[]	[]
parso.python.tree	[]	[]
parso.python.token	[]	[]
parso.python.pep8	[]	[]
...parso_fuzz	['parso_fuzz']	[]
itertools	[]	[]
...parso_pep8_fuzz	['parso_pep8_fuzz']	[]
parso.python.parser	['parso_diff_fuzz']	[]
parso.utils	['parso_pep8_fuzz', 'parso_diff_fuzz', 'parso_extended_fuzz', 'parso_fuzz']	[]
parso.tree	[]	[]
os	[]	[]
logging	[]	[]
gc	[]	[]
collections	[]	[]
parso._compatibility	[]	[]
parso.cache	[]	[]
parso.grammar	['parso_pep8_fuzz', 'parso_diff_fuzz', 'parso_extended_fuzz', 'parso_fuzz']	[]
pickle	[]	[]
time	[]	[]
typing	[]	[]
shutil	[]	[]
...parso_diff_fuzz	['parso_diff_fuzz']	[]
ast	[]	[]
parso.python.diff	['parso_diff_fuzz']	[]
difflib	[]	[]
parso.python.tokenize	[]	[]
parso.python.prefix	[]	[]
re	[]	[]
parso.python	[]	[]
pathlib	[]	[]
parso.pgen2.generator	[]	[]
warnings	[]	[]
codecs	[]	[]
parso.pgen2.grammar_parser	[]	[]
parso.pgen2	[]	[]
atheris	[]	[]
parso.normalizer	[]	[]

Directories in report

Directory