High level conclusions

Fuzzer civetweb_fuzz1 is blocked:

The runtime code coverage of civetweb_fuzz1 covers 8.035% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzers reach 19.92% of cyclomatic complexity.

Fuzzers reach 20.13% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

61 / 303

Cyclomatic complexity statically reachable by fuzzers

553 / 2776

Runtime code coverage of functions

117 / 303

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: civetweb_fuzz1

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	276	97.1%
gold	[1:9]	7	2.46%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	1	0.35%
All colors	284	100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity	Unique Reachable Complexities	Unique Reachable Functions	All non-covered Complexity	All Reachable Complexity	Function Name	Function Callsite	Blocked Branch
207	207	6 : View List ['__errno_location', 'setgid', 'strerror', 'mg_cry_internal_wrap', 'setgroups', 'setuid']	207	207	set_uid_option	call site: 00000	/src/civetweb/src/civetweb.c:16677
106	106	1 : View List ['initialize_openssl']	106	110	mg_init_library	call site: 00000	/src/civetweb/src/civetweb.c:23129
63	63	1 : View List ['mg_cry_internal_wrap']	63	63	mg_vsnprintf	call site: 00012	/src/civetweb/src/civetweb.c:3195
4	4	2 : View List ['pthread_mutexattr_destroy', 'pthread_key_delete']	6	10	mg_init_library	call site: 00000	/src/civetweb/src/civetweb.c:23074
4	4	2 : View List ['strchr', 'strlen']	6	6	next_option	call site: 00000	/src/civetweb/src/civetweb.c:4003
2	2	1 : View List ['htonl']	4	6	parse_port_string	call site: 00000	/src/civetweb/src/civetweb.c:15862
2	2	1 : View List ['abort']	2	2	civetweb_init	call site: 00000	/src/civetweb/fuzztest/fuzzmain.c:92
2	2	1 : View List ['memchr']	2	2	next_option	call site: 00000	/src/civetweb/src/civetweb.c:4008
0	8	1 : View List ['close_all_listening_sockets']	0	8	set_ports_option	call site: 00000	/src/civetweb/src/civetweb.c:16428
0	0	None	3181	4497	mg_start2	call site: 00000	/src/civetweb/src/civetweb.c:21137
0	0	None	3104	4146	mg_start2	call site: 00000	/src/civetweb/src/civetweb.c:21214
0	0	None	3104	4146	mg_start2	call site: 00000	/src/civetweb/src/civetweb.c:21292

Runtime coverage analysis

Covered functions

47

Functions that are reachable but not covered

103

Reachable functions

112

Percentage of reachable functions covered

8.04%

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
fuzztest/fuzzmain.c	3
src/civetweb.c	60

Fuzzer: civetweb_fuzz3

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	159	61.8%
gold	[1:9]	8	3.11%
yellow	[10:29]	79	30.7%
greenyellow	[30:49]	3	1.16%
lawngreen	50+	8	3.11%
All colors	257	100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity	Unique Reachable Complexities	Unique Reachable Functions	All non-covered Complexity	All Reachable Complexity	Function Name	Function Callsite	Blocked Branch
239	245	5 : View List ['mg_free', 'sslize', 'ssl_error', 'close', 'ssl_use_pem_file']	239	245	mg_connect_client_impl	call site: 00093	/src/civetweb/src/civetweb.c:18605
65	65	2 : View List ['strerror', 'mg_cry_internal_wrap']	312	320	mg_connect_client_impl	call site: 00085	/src/civetweb/src/civetweb.c:18576
63	63	1 : View List ['mg_cry_internal_wrap']	63	63	mg_vsnprintf	call site: 00011	/src/civetweb/src/civetweb.c:3195
14	38	7 : View List ['send', 'ferror', '__errno_location', 'fwrite', 'mg_get_current_time_ns', 'mg_poll', 'usleep']	14	38	push_inner	call site: 00168	/src/civetweb/src/civetweb.c:6232
11	11	1 : View List ['alloc_vprintf2']	11	11	alloc_vprintf	call site: 00147	/src/civetweb/src/civetweb.c:7178
8	8	4 : View List ['strerror', '__errno_location', 'abort', 'close']	8	8	mock_server_init	call site: 00000	/src/civetweb/fuzztest/fuzzmain.c:435
6	6	2 : View List ['sleep', 'time']	6	154	mg_write	call site: 00155	/src/civetweb/src/civetweb.c:7019
6	6	3 : View List ['strerror', '__errno_location', 'close']	6	6	connect_socket	call site: 00075	/src/civetweb/src/civetweb.c:9864
4	4	2 : View List ['fileno', 'read']	6	6	pull_inner	call site: 00192	/src/civetweb/src/civetweb.c:6364
2	2	1 : View List ['atoi']	142	142	close_socket_gracefully	call site: 00242	/src/civetweb/src/civetweb.c:18209
2	2	1 : View List ['strtod']	6	100	read_message	call site: 00188	/src/civetweb/src/civetweb.c:11445
2	2	1 : View List ['atoi']	4	64	push_all	call site: 00157	/src/civetweb/src/civetweb.c:6311

Runtime coverage analysis

Covered functions

46

Functions that are reachable but not covered

65

Reachable functions

107

Percentage of reachable functions covered

39.25%

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
fuzztest/fuzzmain.c	2
src/civetweb.c	57

Fuzzer: civetweb_fuzz2

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	175	61.6%
gold	[1:9]	81	28.5%
yellow	[10:29]	22	7.74%
greenyellow	[30:49]	2	0.70%
lawngreen	50+	4	1.40%
All colors	284	100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity	Unique Reachable Complexities	Unique Reachable Functions	All non-covered Complexity	All Reachable Complexity	Function Name	Function Callsite	Blocked Branch
239	245	5 : View List ['mg_free', 'sslize', 'ssl_error', 'close', 'ssl_use_pem_file']	239	245	mg_connect_client_impl	call site: 00094	/src/civetweb/src/civetweb.c:18605
207	207	6 : View List ['__errno_location', 'setgid', 'strerror', 'mg_cry_internal_wrap', 'setgroups', 'setuid']	207	207	set_uid_option	call site: 00000	/src/civetweb/src/civetweb.c:16677
106	106	1 : View List ['initialize_openssl']	106	110	mg_init_library	call site: 00000	/src/civetweb/src/civetweb.c:23129
65	65	2 : View List ['strerror', 'mg_cry_internal_wrap']	312	320	mg_connect_client_impl	call site: 00086	/src/civetweb/src/civetweb.c:18576
63	63	1 : View List ['mg_cry_internal_wrap']	63	65	worker_thread_run	call site: 00000	/src/civetweb/src/civetweb.c:20260
63	63	1 : View List ['mg_cry_internal_wrap']	63	63	mg_vsnprintf	call site: 00012	/src/civetweb/src/civetweb.c:3195
16	36	4 : View List ['mg_unlock_context', 'mg_strncasecmp', 'strlen', 'mg_lock_context']	16	36	switch_domain_context	call site: 00000	/src/civetweb/src/civetweb.c:14501
14	38	7 : View List ['send', 'ferror', '__errno_location', 'fwrite', 'mg_get_current_time_ns', 'mg_poll', 'usleep']	14	38	push_inner	call site: 00197	/src/civetweb/src/civetweb.c:6232
14	14	2 : View List ['strchr', 'mg_stat']	915	1626	mg_send_http_error_impl	call site: 00000	/src/civetweb/src/civetweb.c:4555
11	11	1 : View List ['alloc_vprintf2']	11	11	alloc_vprintf	call site: 00176	/src/civetweb/src/civetweb.c:7178
6	6	2 : View List ['sleep', 'time']	6	154	mg_write	call site: 00184	/src/civetweb/src/civetweb.c:7019
6	6	3 : View List ['strerror', '__errno_location', 'close']	6	6	connect_socket	call site: 00076	/src/civetweb/src/civetweb.c:9864

Runtime coverage analysis

Covered functions

117

Functions that are reachable but not covered

64

Reachable functions

112

Percentage of reachable functions covered

42.86%

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
fuzztest/fuzzmain.c	3
src/civetweb.c	60

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
LLVMFuzzerInitialize	/src/civetweb/fuzztest/fuzzmain.c	2	['N/A', 'N/A']	20	0	20	3	2	369	0	2416	1889
mg_handle_form_request	/src/civetweb/src/handle_form.inl	2	['N/A', 'N/A']	6	0	2393	391	143	63	0	480	173
mg_set_websocket_handler	/src/civetweb/src/civetweb.c	7	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	7	0	40	3	2	36	0	148	51
mg_modify_passwords_file	/src/civetweb/src/civetweb.c	4	['N/A', 'N/A', 'N/A', 'N/A']	4	0	89	16	7	24	0	106	49

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

Functions statically reachable by fuzzers

260 / 303

Cyclomatic complexity statically reachable by fuzzers

2549 / 2776

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.

fuzztest/fuzzmain.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=['mg_poll', 'mg_get_current_time_ns', 'mg_vsnprintf', 'set_close_on_exec', 'mg_calloc']

fuzztest/fuzzmain.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=['lowercase', 'mg_vsnprintf', 'mg_connect_client_impl', 'connect_socket', 'close_socket_gracefully', 'alloc_vprintf', 'push_inner', 'set_non_blocking_mode', 'read_message']

fuzztest/fuzzmain.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=['lowercase', 'mg_connect_client_impl', 'mg_vsnprintf', 'sockaddr_to_string', 'connect_socket', 'close_socket_gracefully', 'pull_all', 'alloc_vprintf', 'push_inner', 'set_non_blocking_mode']

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
mg_start2	395	102	25.82%	['civetweb_fuzz2', 'civetweb_fuzz1']
mg_vsnprintf	33	17	51.51%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
init_ssl_ctx	74	13	17.56%	['civetweb_fuzz2', 'civetweb_fuzz1']
set_ports_option	175	72	41.14%	['civetweb_fuzz2', 'civetweb_fuzz1']
parse_port_string	94	39	41.48%	['civetweb_fuzz2', 'civetweb_fuzz1']
set_uid_option	38	13	34.21%	['civetweb_fuzz2', 'civetweb_fuzz1']
mg_write	62	20	32.25%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
pull_inner	110	35	31.81%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
push_inner	96	27	28.12%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
close_socket_gracefully	53	19	35.84%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
mg_connect_client_impl	162	54	33.33%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
connect_socket	161	57	35.40%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
get_message	64	28	43.75%	['civetweb_fuzz2', 'civetweb_fuzz3', 'civetweb_fuzz1']
test_civetweb_client	63	26	41.26%	['civetweb_fuzz2', 'civetweb_fuzz1']
mg_get_response_code_text	154	6	3.896%	['civetweb_fuzz2']
mg_read	103	6	5.825%	['civetweb_fuzz2', 'civetweb_fuzz1']
mg_send_http_error_impl	129	55	42.63%	['civetweb_fuzz2']
worker_thread_run	107	57	53.27%	['civetweb_fuzz2']
process_new_connection	121	62	51.23%	['civetweb_fuzz2']
get_request	67	31	46.26%	['civetweb_fuzz2']
switch_domain_context	43	9	20.93%	['civetweb_fuzz2']
get_uri_type	38	18	47.36%	['civetweb_fuzz2']
mg_response_header_add	44	23	52.27%	['civetweb_fuzz2']

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/civetweb/src/civetweb.c	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']
/src/civetweb/src/match.inl	[]	[]
/src/civetweb/src/response.inl	[]	[]
/src/civetweb/src/sort.inl	[]	[]
/src/civetweb/src/handle_form.inl	[]	[]
/src/civetweb/fuzztest/fuzzmain.c	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']
/src/civetweb/src/md5.inl	[]	[]

Directories in report

Directory
/src/civetweb/fuzztest/
/src/civetweb/src/