High level conclusions

Fuzzers reach 58.84% code coverage.

Reachability and coverage overview

Functions statically reachable by fuzzers

86 / 746

Cyclomatic complexity statically reachable by fuzzers

305 / 2529

Runtime code coverage of functions

439 / 746

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_env_jinja_lexer

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	14	4.30%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	311	95.6%
All colors	325	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
3	17	jinja2.environment.Environment._tokenize	call site: 00017	jinja2.lexer.TokenStream.__init__
2	286	jinja2.parser.Parser._fail_ut_eof	call site: 00286	.map
1	12	jinja2.environment.Environment.preprocess	call site: 00012	jinja2.environment.Environment.iter_extensions
1	15	jinja2.environment.Environment.iter_extensions	call site: 00015	.str
1	119	jinja2.parser.Parser.parse_subscript	call site: 00119	jinja2.parser.Parser.fail
1	131	jinja2.parser.Parser.parse_call_args	call site: 00131	jinja2.lexer.TokenStream.look
1	162	jinja2.parser.Parser.parse_test	call site: 00162	jinja2.lexer.Token.test_any
1	232	jinja2.parser.Parser.parse_tuple	call site: 00232	jinja2.lexer.describe_token
1	253	jinja2.parser.Parser.parse_assign_target	call site: 00253	jinja2.parser.Parser.parse_primary
1	264	jinja2.parser.Parser.parse_assign_target	call site: 00264	.type
1	301	jinja2.parser.Parser.subparse	call site: 00301	body.extend

Runtime coverage analysis

Covered functions

474

Functions that are reachable but not covered

45

Reachable functions

115

Percentage of reachable functions covered

60.87%

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
...fuzz_env_jinja_lexer	6
jinja2.environment	20
jinja2.parser	72
jinja2.lexer	12
jinja2.nodes	9
jinja2.compiler	4

Fuzzer: fuzz_jinja_compile_templates

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	31	8.24%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	345	91.7%
All colors	376	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
8	21	jinja2.environment.Environment.__init__	call site: 00021	jinja2.utils.import_string
3	32	...fuzz_jinja_compile_templates.TestOneInput	call site: 00032	zipfile.ZipFile
3	56	jinja2.environment.Environment._tokenize	call site: 00056	jinja2.lexer.TokenStream.__init__
2	41	jinja2.loaders.DictLoader.list_templates	call site: 00041	jinja2.environment.Environment.list_templates.filter_func
2	325	jinja2.parser.Parser._fail_ut_eof	call site: 00325	.map
2	366	jinja2.environment.Environment.compile_templates	call site: 00366	zipfile.ZipInfo
1	36	jinja2.environment.Environment.compile_templates	call site: 00036	os.makedirs
1	51	jinja2.environment.Environment.preprocess	call site: 00051	jinja2.environment.Environment.iter_extensions
1	54	jinja2.environment.Environment.iter_extensions	call site: 00054	.str
1	158	jinja2.parser.Parser.parse_subscript	call site: 00158	jinja2.parser.Parser.fail
1	170	jinja2.parser.Parser.parse_call_args	call site: 00170	jinja2.lexer.TokenStream.look
1	201	jinja2.parser.Parser.parse_test	call site: 00201	jinja2.lexer.Token.test_any

Runtime coverage analysis

Covered functions

474

Functions that are reachable but not covered

69

Reachable functions

155

Percentage of reachable functions covered

55.48%

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
...fuzz_jinja_compile_templates	12
jinja2.environment	47
jinja2.utils	7
jinja2.loaders	5
jinja2.parser	72
jinja2.lexer	12
jinja2.nodes	9
jinja2.compiler	4

Fuzzer: fuzz_jinja_compile_expr

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	17	5.13%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	314	94.8%
All colors	331	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
3	0	EP	call site: 00000	jinja2.environment.Environment.compile_expression
3	12	jinja2.environment.Environment._tokenize	call site: 00012	jinja2.lexer.TokenStream.__init__
2	298	jinja2.parser.Parser._fail_ut_eof	call site: 00298	.map
1	7	jinja2.environment.Environment.preprocess	call site: 00007	jinja2.environment.Environment.iter_extensions
1	10	jinja2.environment.Environment.iter_extensions	call site: 00010	.str
1	79	jinja2.parser.Parser.parse_tuple	call site: 00079	jinja2.lexer.describe_token
1	130	jinja2.parser.Parser.parse_subscript	call site: 00130	jinja2.parser.Parser.fail
1	142	jinja2.parser.Parser.parse_call_args	call site: 00142	jinja2.lexer.TokenStream.look
1	173	jinja2.parser.Parser.parse_test	call site: 00173	jinja2.lexer.Token.test_any
1	265	jinja2.parser.Parser.parse_assign_target	call site: 00265	jinja2.parser.Parser.parse_primary
1	276	jinja2.parser.Parser.parse_assign_target	call site: 00276	.type
1	313	jinja2.parser.Parser.subparse	call site: 00313	body.extend

Runtime coverage analysis

Covered functions

474

Functions that are reachable but not covered

42

Reachable functions

115

Percentage of reachable functions covered

63.48%

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
...fuzz_jinja_compile_expr	3
jinja2.environment	25
jinja2.parser	72
jinja2.lexer	12
jinja2.nodes	9
jinja2.compiler	4

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
jinja2.compiler.CodeGenerator.visit_Macro	jinja2.compiler	3	['N/A', 'N/A', 'N/A']	7	0	5	2	4	58	0	187	152
jinja2.ext.InternationalizationExtension.parse	jinja2.ext	2	['N/A', 'N/A']	2	0	14	20	11	35	0	125	84
jinja2.compiler.optimizeconst.new_func	jinja2.compiler	4	['N/A', 'N/A', 'N/A', 'N/A']	5	0	0	2	4	49	0	167	81
jinja2.filters.do_urlize	jinja2.filters	7	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	3	0	3	5	5	27	0	90	72
jinja2.filters.async_select_or_reject	jinja2.filters	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	3	0	1	2	4	25	4	81	72
jinja2.debug.rewrite_traceback_stack	jinja2.debug	1	['N/A']	3	0	4	3	4	24	0	80	68
jinja2.lexer.Lexer.tokeniter	jinja2.lexer	5	['N/A', 'N/A', 'N/A', 'N/A', 'N/A']	1	0	11	27	14	19	1	71	56
jinja2.ext.babel_extract	jinja2.ext	4	['N/A', 'N/A', 'N/A', 'N/A']	39	0	2	5	5	133	0	451	55
jinja2.compiler.CodeGenerator.visit_Template	jinja2.compiler	3	['N/A', 'N/A', 'N/A']	6	0	44	11	7	56	0	182	53
jinja2.nodes._FilterTestCommon.as_const	jinja2.nodes	2	['N/A', 'N/A']	3	0	3	6	5	16	0	55	37

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

Functions statically reachable by fuzzers

167 / 746

Cyclomatic complexity statically reachable by fuzzers

624 / 2529

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.

/src/fuzz_env_jinja_lexer.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=['jinja2.environment.Environment._tokenize', 'jinja2.parser.Parser._fail_ut_eof', 'jinja2.environment.Environment.preprocess', 'jinja2.environment.Environment.iter_extensions', 'jinja2.parser.Parser.parse_subscript', 'jinja2.parser.Parser.parse_call_args', 'jinja2.parser.Parser.parse_test', 'jinja2.parser.Parser.parse_tuple', 'jinja2.parser.Parser.parse_assign_target']

/src/fuzz_jinja_compile_templates.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=['jinja2.environment.Environment.__init__', '...fuzz_jinja_compile_templates.TestOneInput', 'jinja2.environment.Environment._tokenize', 'jinja2.loaders.DictLoader.list_templates', 'jinja2.parser.Parser._fail_ut_eof', 'jinja2.environment.Environment.compile_templates', 'jinja2.environment.Environment.preprocess', 'jinja2.environment.Environment.iter_extensions', 'jinja2.parser.Parser.parse_subscript']

/src/fuzz_jinja_compile_expr.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=['jinja2.environment.Environment._tokenize', 'jinja2.parser.Parser._fail_ut_eof', 'jinja2.environment.Environment.preprocess', 'jinja2.environment.Environment.iter_extensions', 'jinja2.parser.Parser.parse_tuple', 'jinja2.parser.Parser.parse_subscript', 'jinja2.parser.Parser.parse_call_args', 'jinja2.parser.Parser.parse_test', 'jinja2.parser.Parser.parse_assign_target']

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
jinja2.utils.urlize.trim_url	37	0	0.0%	[]
jinja2.utils.generate_lorem_ipsum	36	0	0.0%	[]
jinja2.compiler.CodeGenerator.visit_FromImport	31	0	0.0%	[]
jinja2.loaders.PackageLoader.__init__	33	0	0.0%	[]
expr.split	32	11	34.37%	['fuzz_jinja_compile_expr', 'fuzz_jinja_compile_templates', 'fuzz_env_jinja_lexer']
s.splitlines	36	16	44.44%	['fuzz_jinja_compile_expr', 'fuzz_jinja_compile_templates', 'fuzz_env_jinja_lexer']

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
	[]	[]
collections	[]	[]
jinja2.sandbox	[]	[]
jinja2.lexer	['fuzz_env_jinja_lexer', 'fuzz_jinja_compile_templates', 'fuzz_jinja_compile_expr']	[]
zipfile	[]	[]
pprint	[]	[]
jinja2.meta	[]	[]
jinja2.debug	[]	[]
jinja2.filters	[]	[]
random	[]	[]
sys	[]	[]
jinja2._identifier	[]	[]
stat	[]	[]
jinja2.idtracking	[]	[]
re	[]	[]
weakref	[]	[]
enum	[]	[]
hashlib	[]	[]
jinja2.compiler	['fuzz_env_jinja_lexer', 'fuzz_jinja_compile_templates', 'fuzz_jinja_compile_expr']	[]
jinja2.runtime	[]	[]
warnings	[]	[]
textwrap	[]	[]
jinja2.nativetypes	[]	[]
atheris	[]	[]
jinja2.constants	[]	[]
typing	[]	[]
jinja2.utils	['fuzz_jinja_compile_templates']	[]
_string	[]	[]
os	[]	[]
asyncio	[]	[]
tempfile	[]	[]
json	[]	[]
inspect	[]	[]
jinja2.visitor	[]	[]
functools	[]	[]
jinja2.loaders	['fuzz_jinja_compile_templates']	[]
markupsafe	[]	[]
posixpath	[]	[]
jinja2.optimizer	[]	[]
fnmatch	[]	[]
io	[]	[]
logging	[]	[]
...fuzz_jinja_compile_templates	['fuzz_jinja_compile_templates']	[]
itertools	[]	[]
jinja2.ext	[]	[]
gettext	[]	[]
jinja2.tests	[]	[]
string	[]	[]
jinja2.bccache	[]	[]
jinja2.parser	['fuzz_env_jinja_lexer', 'fuzz_jinja_compile_templates', 'fuzz_jinja_compile_expr']	[]
contextlib	[]	[]
pickle	[]	[]
importlib	[]	[]
threading	[]	[]
jinja2	[]	[]
jinja2.async_utils	[]	[]
jinja2.defaults	[]	[]
	[]	[]
jinja2.environment	['fuzz_env_jinja_lexer', 'fuzz_jinja_compile_templates', 'fuzz_jinja_compile_expr']	[]
ast	[]	[]
urllib	[]	[]
...fuzz_env_jinja_lexer	['fuzz_env_jinja_lexer']	[]
jinja2.exceptions	[]	[]
jinja2.nodes	['fuzz_env_jinja_lexer', 'fuzz_jinja_compile_templates', 'fuzz_jinja_compile_expr']	[]
...fuzz_jinja_compile_expr	['fuzz_jinja_compile_expr']	[]
traceback	[]	[]
keyword	[]	[]
marshal	[]	[]

Directories in report

Directory