High level conclusions

Fuzzers reach 51.95% code coverage.

Fuzzers reach 55.30% of cyclomatic complexity.

Fuzzers reach 53.36% of all functions.

Fuzzer fuzz_pcap is blocked:

The runtime code coverage of fuzz_pcap covers 27.77% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer fuzz_filter is blocked:

The runtime code coverage of fuzz_filter 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

301 / 564

Cyclomatic complexity statically reachable by fuzzers

2021 / 3654

Runtime code coverage of functions

293 / 564

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_filter

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	1934	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	1934	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
1933	0	EP	call site: 00000	pcap_compile

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

322

Reachable functions

322

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
build/../testprogs/fuzz/fuzz_filter.c	1
pcap.c	11
gencode.c	184
build/scanner.c	24
fmtutils.c	2
build/grammar.c	2
missing/strlcpy.c	1
scanner.l	2
nametoaddr.c	12
extract.h	2
build/grammar.y	4
optimize.c	47

Fuzzer: fuzz_pcap

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	29	49.1%
gold	[1:9]	3	5.08%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	27	45.7%
All colors	59	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
8	21	pcap_open_offline_with_tstamp_precision	call site: 00021	pcapint_fmt_errmsg_for_errno
8	44	pcapint_offline_read	call site: 00044	pcapint_filter_with_aux_data
3	6	bufferToFile	call site: 00006	__errno_location
2	10	bufferToFile	call site: 00010	__errno_location
2	18	pcap_open_offline	call site: 00018	snprintf
2	33	pcap_fopen_offline_with_tstamp_precision	call site: 00033	pcapint_fmt_errmsg_for_errno
1	13	bufferToFile	call site: 00013	fclose
1	15	bufferToFile	call site: 00015	unlink
1	30	pcap_open_offline_with_tstamp_precision	call site: 00030	snprintf
1	55	LLVMFuzzerTestOneInput	call site: 00055	fprintf

Runtime coverage analysis

Covered functions

45

Functions that are reachable but not covered

26

Reachable functions

36

Percentage of reachable functions covered

27.78%

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
build/../testprogs/fuzz/fuzz_pcap.c	2
savefile.c	4
fmtutils.c	2
pcap.c	4
bpf_filter.c	2
extract.h	2

Fuzzer: fuzz_both

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	618	31.2%
gold	[1:9]	62	3.13%
yellow	[10:29]	75	3.79%
greenyellow	[30:49]	83	4.19%
lawngreen	50+	1139	57.6%
All colors	1977	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
76	1402	gen_pppoes	call site: 01402	gen_geneve
54	1236	gen_mtp2type_abbrev	call site: 01236	gen_broadcast
46	905	gen_scode	call site: 00905	gen_gateway
37	616	gen_ncode	call site: 00616	gen_portrange
27	1194	gen_atmmulti_abbrev	call site: 01194	gen_atmtype_abbrev
23	1313	gen_byteop	call site: 01313	gen_vlan
23	1349	gen_vlan_vid_test	call site: 01349	gen_mcmp
22	99	sdup	call site: 00099	stou
17	122	pcap_lex	call site: 00122	pcap_restart
15	987	gen_mcode	call site: 00987	gen_ncode
14	1625	gen_llc_u_subtype	call site: 01625	gen_llc_s_subtype
11	80	pcap_parse	call site: 00080	pcap__create_buffer

Runtime coverage analysis

Covered functions

294

Functions that are reachable but not covered

75

Reachable functions

334

Percentage of reachable functions covered

77.54%

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
build/../testprogs/fuzz/fuzz_both.c	2
savefile.c	4
fmtutils.c	2
pcap.c	9
gencode.c	184
build/scanner.c	24
build/grammar.c	2
missing/strlcpy.c	1
scanner.l	2
nametoaddr.c	12
extract.h	2
build/grammar.y	4
optimize.c	47
bpf_filter.c	2

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
pcap_findalldevs_ex	/src/libpcap/pcap.c	4	['N/A', 'N/A', 'N/A', 'N/A']	9	0	475	62	24	61	0	329	265
pcap_activate_linux	/src/libpcap/pcap-linux.c	1	['N/A']	8	0	343	45	15	56	0	291	244
pcap_ng_next_packet	/src/libpcap/sf-pcapng.c	3	['N/A', 'N/A', 'N/A']	6	0	992	70	19	35	0	208	181
pcap_open	/src/libpcap/pcap.c	6	['N/A', 'int', 'int', 'int', 'N/A', 'N/A']	8	0	254	46	16	47	0	243	97
pcap_read_linux_mmap_v3	/src/libpcap/pcap-linux.c	4	['N/A', 'int', 'N/A', 'N/A']	6	0	522	77	28	27	0	166	92
netfilter_activate	/src/libpcap/pcap-netfilter-linux.c	1	['N/A']	4	0	617	89	35	27	0	117	77
pcap_setfilter_linux	/src/libpcap/pcap-linux.c	2	['N/A', 'N/A']	5	0	344	65	21	22	0	105	74
pcap_dump_open_append	/src/libpcap/sf-pcap.c	2	['N/A', 'N/A']	4	0	424	60	20	18	0	72	45
netfilter_read_linux	/src/libpcap/pcap-netfilter-linux.c	4	['N/A', 'int', 'N/A', 'N/A']	4	0	735	112	37	24	0	132	41
pcap_check_header	/src/libpcap/sf-pcap.c	5	['N/A', 'N/A', 'int', 'N/A', 'N/A']	6	0	633	77	25	16	0	72	36

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

Functions statically reachable by fuzzers

422 / 564

Cyclomatic complexity statically reachable by fuzzers

3099 / 3654

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.

build/../testprogs/fuzz/fuzz_filter.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

build/../testprogs/fuzz/fuzz_pcap.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=['pcap_open_offline_with_tstamp_precision', 'pcapint_offline_read', 'bufferToFile', 'pcap_open_offline', 'pcap_fopen_offline_with_tstamp_precision', 'LLVMFuzzerTestOneInput']

build/../testprogs/fuzz/fuzz_both.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=['gen_pppoes', 'gen_mtp2type_abbrev', 'gen_scode', 'gen_ncode', 'gen_atmmulti_abbrev', 'gen_byteop', 'gen_vlan_vid_test', 'sdup', 'pcap_lex', 'gen_mcode']

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
pcap_open_offline_with_tstamp_precision	32	16	50.0%	['fuzz_pcap', 'fuzz_both']
yy_get_next_buffer	90	19	21.11%	['fuzz_filter', 'fuzz_both']
gen_scode	121	66	54.54%	['fuzz_filter', 'fuzz_both']
gen_atmmulti_abbrev	52	22	42.30%	['fuzz_filter', 'fuzz_both']

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/libpcap/build/grammar.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/scanner.l	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/missing/strlcat.c	[]	[]
/src/libpcap/pcap-netfilter-linux.c	[]	[]
/src/libpcap/pcap-usb-linux.c	[]	[]
/src/libpcap/fad-getad.c	[]	[]
/src/libpcap/build/grammar.y	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/build/../testprogs/fuzz/fuzz_filter.c	['fuzz_filter']	[]
/src/libpcap/missing/strlcpy.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/bpf_filter.c	['fuzz_pcap', 'fuzz_both']	['fuzz_both']
/src/libpcap/pcap-linux.c	[]	[]
/src/libpcap/savefile.c	['fuzz_pcap', 'fuzz_both']	['fuzz_pcap', 'fuzz_both']
/src/libpcap/sf-pcap.c	[]	[]
/src/libpcap/pcap-util.c	[]	[]
/src/libpcap/pcap.c	['fuzz_filter', 'fuzz_pcap', 'fuzz_both']	['fuzz_pcap', 'fuzz_both']
/src/libpcap/pcap-usb-linux-common.h	[]	[]
/src/libpcap/optimize.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/build/scanner.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/pcap-common.c	[]	[]
/src/libpcap/gencode.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']
/src/libpcap/build/../testprogs/fuzz/fuzz_pcap.c	['fuzz_pcap']	[]
/src/libpcap/fmtutils.c	['fuzz_filter', 'fuzz_pcap', 'fuzz_both']	[]
/src/libpcap/build/../testprogs/fuzz/fuzz_both.c	['fuzz_both']	[]
/src/libpcap/extract.h	['fuzz_filter', 'fuzz_pcap', 'fuzz_both']	['fuzz_pcap', 'fuzz_both']
/src/libpcap/sf-pcapng.c	[]	[]
/src/libpcap/nametoaddr.c	['fuzz_filter', 'fuzz_both']	['fuzz_both']

Directories in report

Directory
/src/libpcap/missing/
/src/libpcap/build/
/src/libpcap/
/src/libpcap/build/../testprogs/fuzz/