High level conclusions

Fuzzers reach 63.82% code coverage.

Fuzzers reach 70.24% of cyclomatic complexity.

Fuzzers reach 53.19% of all functions.

Fuzzer mozjpeg_compression_fuzzer is blocked:

The runtime code coverage of mozjpeg_compression_fuzzer covers 21.59% 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 22.09% 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 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.

Reachability and coverage overview

Functions statically reachable by fuzzers

25 / 47

Cyclomatic complexity statically reachable by fuzzers

321 / 457

Runtime code coverage of functions

30 / 47

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: 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	212	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	212	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
211	0	EP	call site: 00000	optimize

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

86

Reachable functions

86

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_compression.c	1
fuzz/fuzz_manager.c	2
jpegoptim.c	5
misc.c	11
jpegsrc.c	2
jpegmarker.c	4
jpegdest.c	1

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	100	47.1%
gold	[1:9]	10	4.71%
yellow	[10:29]	1	0.47%
greenyellow	[30:49]	5	2.35%
lawngreen	50+	96	45.2%
All colors	212	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
29	143	optimize	call site: 00143	copy_file
9	188	optimize	call site: 00188	delete_file
6	39	optimize	call site: 00039	fatal
6	81	optimize	call site: 00081	fatal
6	134	optimize	call site: 00134	fprintf
5	23	optimize	call site: 00023	warn
5	127	optimize	call site: 00127	fprintf
4	183	optimize	call site: 00183	fatal
3	89	optimize	call site: 00089	file_exists
2	6	generate_temp_file_name	call site: 00006	perror
2	64	parse_markers	call site: 00064	fprintf
2	76	optimize	call site: 00076	fprintf

Runtime coverage analysis

Covered functions

31

Functions that are reachable but not covered

67

Reachable functions

86

Percentage of reachable functions covered

22.09%

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	11
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	101	46.7%
gold	[1:9]	12	5.55%
yellow	[10:29]	11	5.09%
greenyellow	[30:49]	16	7.40%
lawngreen	50+	76	35.1%
All colors	216	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
29	147	optimize	call site: 00147	copy_file
9	192	optimize	call site: 00192	delete_file
6	39	optimize	call site: 00039	fatal
6	81	optimize	call site: 00081	fatal
6	138	optimize	call site: 00138	fprintf
5	23	optimize	call site: 00023	warn
5	131	optimize	call site: 00131	fprintf
4	187	optimize	call site: 00187	fatal
3	75	optimize	call site: 00075	jpeg_read_coefficients
3	89	optimize	call site: 00089	file_exists
2	6	generate_temp_file_name	call site: 00006	perror
2	64	parse_markers	call site: 00064	fprintf

Runtime coverage analysis

Covered functions

31

Functions that are reachable but not covered

69

Reachable functions

88

Percentage of reachable functions covered

21.59%

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	11
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	547	118	31	21	0	83	55

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

Functions statically reachable by fuzzers

30 / 47

Cyclomatic complexity statically reachable by fuzzers

366 / 457

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

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', 'generate_temp_file_name']

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']

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

Directories in report

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