High level conclusions

Fuzzers reach 59.76% of cyclomatic complexity.

Fuzzers reach 53.57% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

135 / 252

Cyclomatic complexity statically reachable by fuzzers

866 / 1449

Runtime code coverage of functions

112 / 252

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_utils

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	8	8.98%
gold	[1:9]	1	1.12%
yellow	[10:29]	1	1.12%
greenyellow	[30:49]	6	6.74%
lawngreen	50+	73	82.0%
All colors	89	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
4	3	buffer_init	call site: 00003	ck_bt_stderr
3	20	buffer_path_simplify	call site: 00020	buffer_blank
1	77	buffer_append_base64_enc	call site: 00077	ck_assert_failed

Runtime coverage analysis

Covered functions

30

Functions that are reachable but not covered

10

Reachable functions

40

Percentage of reachable functions covered

75.0%

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_utils.c	1
lighttpd1.4buffer.c	21
lighttpd1.4ck.c	2
lighttpd1.4./buffer.h	6
lighttpd1.4base64.c	4

Fuzzer: fuzz_burl

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	10	13.3%
gold	[1:9]	2	2.66%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	63	84.0%
All colors	75	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
4	3	buffer_init	call site: 00003	ck_bt_stderr
3	51	buffer_path_simplify	call site: 00051	buffer_blank
3	55	buffer_extend	call site: 00055	buffer_string_prepare_copy

Runtime coverage analysis

Covered functions

32

Functions that are reachable but not covered

11

Reachable functions

43

Percentage of reachable functions covered

74.42%

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_burl.c	2
lighttpd1.4buffer.c	12
lighttpd1.4ck.c	2
lighttpd1.4burl.c	13
lighttpd1.4./buffer.h	7

Fuzzer: fuzz_request

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	112	32.4%
gold	[1:9]	12	3.47%
yellow	[10:29]	15	4.34%
greenyellow	[30:49]	11	3.18%
lawngreen	50+	195	56.5%
All colors	345	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
16	47	itostr	call site: 00047	log_buffer_vsprintf
13	318	http_request_headers_process	call site: 00318	log_pri_multiline
11	14	http_request_parse_reqline	call site: 00014	log_debug
11	64	buffer_append_string_len	call site: 00064	log_error_append_strerror
10	218	burl_contains_ctrls	call site: 00218	burl_normalize_path
8	76	buffer_append_char	call site: 00076	write_all
8	232	buffer_blank	call site: 00232	buffer_append_string_len
7	169	http_request_parse_single_header	call site: 00169	http_request_header_line_invalid
6	35	buffer_string_prepare_append_resize	call site: 00035	buffer_copy_string_len
6	311	http_request_parse	call site: 00311	http_request_header_line_invalid
4	6	buffer_init	call site: 00006	ck_bt_stderr
4	42	buffer_copy_string_len	call site: 00042	log_buffer_prefix

Runtime coverage analysis

Covered functions

92

Functions that are reachable but not covered

53

Reachable functions

144

Percentage of reachable functions covered

63.19%

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_request.c	1
lighttpd1.4http_header.c	12
lighttpd1.4buffer.c	27
lighttpd1.4ck.c	6
lighttpd1.4request.c	22
lighttpd1.4log.c	12
lighttpd1.4./buffer.h	13
lighttpd1.4http_kv.c	1
lighttpd1.4array.c	12
lighttpd1.4burl.c	13
lighttpd1.4sock_addr.c	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
http_request_parse_header	/src/lighttpd1.4/src/request.c	2	['N/A', 'N/A']	13	0	725	112	38	100	0	440	103
burl_append	/src/lighttpd1.4/src/burl.c	4	['N/A', 'N/A', 'size_t', 'int']	7	0	177	34	13	29	0	138	60

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

Functions statically reachable by fuzzers

150 / 252

Cyclomatic complexity statically reachable by fuzzers

1029 / 1449

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_utils.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=['buffer_init', 'buffer_path_simplify', 'buffer_append_base64_enc']

fuzz_burl.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=['buffer_init', 'buffer_path_simplify', 'buffer_extend']

fuzz_request.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=['itostr', 'http_request_headers_process', 'http_request_parse_reqline', 'buffer_append_string_len', 'burl_contains_ctrls', 'buffer_append_char', 'buffer_blank', 'http_request_parse_single_header', 'buffer_string_prepare_append_resize', 'http_request_parse']

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
http_request_parse_single_header	71	37	52.11%	['fuzz_request']

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/lighttpd1.4/src/buffer.c	['fuzz_utils', 'fuzz_burl', 'fuzz_request']	['fuzz_utils', 'fuzz_burl', 'fuzz_request']
	[]	[]
/src/fuzz_request.c	['fuzz_request']	['fuzz_request']
/src/lighttpd1.4/src/request.c	['fuzz_request']	['fuzz_request']
/src/lighttpd1.4/src/ck.c	['fuzz_utils', 'fuzz_burl', 'fuzz_request']	['fuzz_request']
/src/fuzz_burl.c	['fuzz_burl']	['fuzz_burl']
/src/lighttpd1.4/src/http_header.c	['fuzz_request']	['fuzz_request']
/src/lighttpd1.4/src/./buffer.h	['fuzz_utils', 'fuzz_burl', 'fuzz_request']	[]
/src/lighttpd1.4/src/log.c	['fuzz_request']	[]
/src/lighttpd1.4/src/base64.c	['fuzz_utils']	['fuzz_utils']
/src/lighttpd1.4/src/sock_addr.c	['fuzz_request']	['fuzz_request']
/src/lighttpd1.4/src/array.c	['fuzz_request']	['fuzz_request']
/src/lighttpd1.4/src/./array.h	[]	[]
/src/fuzz_utils.c	['fuzz_utils']	['fuzz_utils']
/src/lighttpd1.4/src/burl.c	['fuzz_burl', 'fuzz_request']	['fuzz_burl', 'fuzz_request']
/src/lighttpd1.4/src/http_kv.c	['fuzz_request']	['fuzz_request']

Directories in report

Directory
/src/lighttpd1.4/src/./
/src/lighttpd1.4/src/
/src/