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 19.75% 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 / 2799

Runtime code coverage of functions

111 / 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	277	97.5%
gold	[1:9]	6	2.11%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	1	0.35%
All colors	284	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
210	73	mg_poll	call site: 00073	mg_get_response
51	12	mg_vsnprintf	call site: 00012	connect_socket
7	64	set_close_on_exec	call site: 00064	mg_cry_internal_wrap
6	0	EP	call site: 00000	test_civetweb_client
3	7	mg_calloc	call site: 00007	mg_snprintf

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	162	63.0%
gold	[1:9]	12	4.66%
yellow	[10:29]	72	28.0%
greenyellow	[30:49]	4	1.55%
lawngreen	50+	7	2.72%
All colors	257	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
32	111	mg_strcasecmp	call site: 00111	refresh_trust
27	11	mg_vsnprintf	call site: 00011	mg_cry_internal_wrap
21	89	mg_connect_client_impl	call site: 00089	sslize
9	75	connect_socket	call site: 00075	mg_snprintf
7	244	close_socket_gracefully	call site: 00244	mg_cry_internal_wrap
6	147	alloc_vprintf	call site: 00147	alloc_vprintf2
6	168	push_inner	call site: 00168	push_all
5	56	set_non_blocking_mode	call site: 00056	mg_snprintf
5	161	push_inner	call site: 00161	clock_gettime
5	192	read_message	call site: 00192	mg_poll
4	49	connect_socket	call site: 00049	mg_snprintf
4	63	set_close_on_exec	call site: 00063	mg_cry_internal_wrap

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	180	63.3%
gold	[1:9]	85	29.9%
yellow	[10:29]	16	5.63%
greenyellow	[30:49]	1	0.35%
lawngreen	50+	2	0.70%
All colors	284	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
30	112	mg_strcasecmp	call site: 00112	refresh_trust
21	90	mg_connect_client_impl	call site: 00090	sslize
17	12	mg_vsnprintf	call site: 00012	mg_cry_internal_wrap
9	30	sockaddr_to_string	call site: 00030	mg_cry_internal_impl
9	76	connect_socket	call site: 00076	mg_snprintf
7	156	close_socket_gracefully	call site: 00156	mg_cry_internal_wrap
7	271	pull_all	call site: 00271	mg_read_inner
6	176	alloc_vprintf	call site: 00176	alloc_vprintf2
6	197	push_inner	call site: 00197	push_all
5	57	set_non_blocking_mode	call site: 00057	mg_snprintf
5	190	push_inner	call site: 00190	clock_gettime
5	221	read_message	call site: 00221	mg_poll

Runtime coverage analysis

Covered functions

111

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.

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	18	3	2	370	0	2435	1908
mg_handle_form_request	/src/civetweb/src/handle_form.inl	2	['N/A', 'N/A']	6	0	2386	398	146	63	0	487	179
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	33	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	84	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

2572 / 2799

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_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=['mg_strcasecmp', '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=['mg_strcasecmp', '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	394	101	25.63%	['civetweb_fuzz1', 'civetweb_fuzz2']
mg_vsnprintf	32	17	53.12%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
init_ssl_ctx	74	13	17.56%	['civetweb_fuzz1', 'civetweb_fuzz2']
set_ports_option	175	72	41.14%	['civetweb_fuzz1', 'civetweb_fuzz2']
parse_port_string	94	38	40.42%	['civetweb_fuzz1', 'civetweb_fuzz2']
set_uid_option	38	13	34.21%	['civetweb_fuzz1', 'civetweb_fuzz2']
mg_write	62	20	32.25%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
pull_inner	110	35	31.81%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
push_inner	96	27	28.12%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
close_socket_gracefully	53	19	35.84%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
mg_connect_client_impl	162	53	32.71%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
connect_socket	161	57	35.40%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
get_message	64	28	43.75%	['civetweb_fuzz1', 'civetweb_fuzz2', 'civetweb_fuzz3']
test_civetweb_client	63	23	36.50%	['civetweb_fuzz1', 'civetweb_fuzz2']
mg_get_response_code_text	154	6	3.896%	['civetweb_fuzz2']
mg_read	103	6	5.825%	['civetweb_fuzz1', 'civetweb_fuzz2']
mg_send_http_error_impl	129	54	41.86%	['civetweb_fuzz2']
send_cors_header	56	30	53.57%	['civetweb_fuzz2']
worker_thread_run	107	57	53.27%	['civetweb_fuzz2']
process_new_connection	121	43	35.53%	['civetweb_fuzz2']
get_request	67	16	23.88%	['civetweb_fuzz2']
parse_http_request	50	17	34.0%	['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/fuzztest/fuzzmain.c	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']	['civetweb_fuzz1', 'civetweb_fuzz3', 'civetweb_fuzz2']
/src/civetweb/src/md5.inl	[]	[]
/src/civetweb/src/handle_form.inl	[]	[]
/src/civetweb/src/response.inl	[]	[]
/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/sort.inl	[]	[]

Directories in report

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