High level conclusions

Fuzzers reach 62.5% code coverage.

Fuzzers reach 69.37% of cyclomatic complexity.

Fuzzers reach 54.16% of all functions.

Fuzzer mozjpeg_compression_fuzzer is blocked:

The runtime code coverage of mozjpeg_compression_fuzzer covers 20.65% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer libjpeg_compression_fuzzer is blocked:

The runtime code coverage of libjpeg_compression_fuzzer covers 21.11% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer libjpegturbo_compression_fuzzer is blocked:

The runtime code coverage of libjpegturbo_compression_fuzzer covers 15.55% 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

26 / 48

Cyclomatic complexity statically reachable by fuzzers

342 / 493

Runtime code coverage of functions

30 / 48

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: libjpegturbo_compression_fuzzer

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	158	67.8%
gold	[1:9]	65	27.8%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	1	0.42%
lawngreen	50+	9	3.86%
All colors	233	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
80	150	optimize	call site: 00150	copy_file
18	117	optimize	call site: 00117	write_markers
8	33	optimize	call site: 00033	fprint_csv_field
6	46	file_size	call site: 00046	fatal
6	78	optimize	call site: 00078	fatal
6	90	optimize	call site: 00090	fatal
6	143	optimize	call site: 00143	fprintf
5	23	optimize	call site: 00023	warn
5	136	optimize	call site: 00136	fprintf
3	98	optimize	call site: 00098	file_exists
2	6	generate_temp_file_name	call site: 00006	perror
2	57	optimize	call site: 00057	jpeg_custom_mem_src

Runtime coverage analysis

Covered functions

21

Functions that are reachable but not covered

76

Reachable functions

90

Percentage of reachable functions covered

15.56%

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_compression.c	1
fuzz/fuzz_manager.c	2
jpegoptim.c	5
misc.c	12
jpegsrc.c	2
jpegmarker.c	4
jpegdest.c	1

Fuzzer: libjpeg_compression_fuzzer

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	121	51.9%
gold	[1:9]	11	4.72%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	101	43.3%
All colors	233	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
31	152	optimize	call site: 00152	copy_file
18	201	rename_file	call site: 00201	delete_file
8	33	optimize	call site: 00033	fprint_csv_field
6	46	file_size	call site: 00046	fatal
6	90	optimize	call site: 00090	fatal
6	143	optimize	call site: 00143	fprintf
5	23	optimize	call site: 00023	warn
5	136	optimize	call site: 00136	fprintf
3	98	optimize	call site: 00098	file_exists
3	191	create_temp_file	call site: 00191	fatal
2	6	generate_temp_file_name	call site: 00006	perror
2	73	parse_markers	call site: 00073	fprintf

Runtime coverage analysis

Covered functions

31

Functions that are reachable but not covered

71

Reachable functions

90

Percentage of reachable functions covered

21.11%

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_compression.c	1
fuzz/fuzz_manager.c	2
jpegoptim.c	5
misc.c	12
jpegsrc.c	2
jpegmarker.c	4
jpegdest.c	1

Fuzzer: mozjpeg_compression_fuzzer

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	121	51.0%
gold	[1:9]	10	4.21%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	106	44.7%
All colors	237	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
31	156	optimize	call site: 00156	copy_file
18	205	rename_file	call site: 00205	delete_file
8	33	optimize	call site: 00033	fprint_csv_field
6	46	file_size	call site: 00046	fatal
6	90	optimize	call site: 00090	fatal
6	147	optimize	call site: 00147	fprintf
5	23	optimize	call site: 00023	warn
5	140	optimize	call site: 00140	fprintf
3	98	optimize	call site: 00098	file_exists
3	195	create_temp_file	call site: 00195	fatal
2	6	generate_temp_file_name	call site: 00006	perror
2	73	parse_markers	call site: 00073	fprintf

Runtime coverage analysis

Covered functions

31

Functions that are reachable but not covered

73

Reachable functions

92

Percentage of reachable functions covered

20.65%

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_compression.c	1
fuzz/fuzz_manager.c	2
jpegoptim.c	5
misc.c	12
jpegsrc.c	2
jpegmarker.c	4
jpegdest.c	1

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
parse_arguments	/src/jpegoptim/jpegoptim.c	4	['int', 'N/A', 'N/A', 'size_t']	3	0	644	136	37	25	0	102	69
wait_for_worker	/src/jpegoptim/jpegoptim.c	1	['N/A']	2	0	484	89	31	14	0	60	39

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

Functions statically reachable by fuzzers

33 / 48

Cyclomatic complexity statically reachable by fuzzers

430 / 493

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_compression.c

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=['optimize', 'file_size']

fuzz/fuzz_compression.c

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=['optimize', 'rename_file', 'file_size', 'create_temp_file']

fuzz/fuzz_compression.c

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=['optimize', 'rename_file', 'file_size', 'create_temp_file']

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

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/jpegoptim/fuzz/fuzz_compression.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
	[]	[]
/src/jpegoptim/jpegsrc.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
/src/jpegoptim/fuzz/fuzz_manager.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
/src/jpegoptim/jpegmarker.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
/src/jpegoptim/jpegoptim.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
/src/jpegoptim/jpegdest.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']
/src/jpegoptim/misc.c	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']	['libjpegturbo_compression_fuzzer', 'libjpeg_compression_fuzzer', 'mozjpeg_compression_fuzzer']

Directories in report

Directory
/src/jpegoptim/
/src/jpegoptim/fuzz/