High level conclusions

Fuzzers reach 54.51% code coverage.

Fuzzers reach 61.68% of cyclomatic complexity.

Fuzzers reach 56.18% of all functions.

Fuzzer fuzz_pcap is blocked:

The runtime code coverage of fuzz_pcap covers 28.57% 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

336 / 598

Cyclomatic complexity statically reachable by fuzzers

2476 / 4014

Runtime code coverage of functions

326 / 598

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	2019	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	2019	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
2018	0	EP	call site: 00000	pcap_compile

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

358

Reachable functions

358

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	12
gencode.c	211
build/scanner.c	24
fmtutils.c	2
build/grammar.c	2
missing/strlcpy.c	1
scanner.l	2
nametoaddr.c	16
extract.h	2
build/grammar.y	4
optimize.c	48
bpf_filter.c	2

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	50.0%
gold	[1:9]	3	5.17%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	26	44.8%
All colors	58	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	43	pcap_next_ex	call site: 00043	pcapint_filter
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	54	LLVMFuzzerTestOneInput	call site: 00054	fprintf

Runtime coverage analysis

Covered functions

47

Functions that are reachable but not covered

25

Reachable functions

35

Percentage of reachable functions covered

28.57%

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	667	32.3%
gold	[1:9]	69	3.34%
yellow	[10:29]	81	3.93%
greenyellow	[30:49]	18	0.87%
lawngreen	50+	1226	59.4%
All colors	2061	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
81	1493	gen_pppoes	call site: 01493	gen_geneve
80	928	gen_scode	call site: 00928	gen_gateway
55	1323	gen_mtp2type_abbrev	call site: 01323	gen_broadcast
27	1281	gen_atmmulti_abbrev	call site: 01281	gen_atmtype_abbrev
25	1401	gen_byteop	call site: 01401	gen_vlan
25	1439	gen_vlan_vid_test	call site: 01439	gen_mcmp
21	103	sdup	call site: 00103	stou
17	125	pcap_lex	call site: 00125	pcap_restart
15	1049	gen_mcode	call site: 01049	gen_ncode
14	1725	gen_llc_u_subtype	call site: 01725	gen_llc_s_subtype
12	1669	gen_p80211_fcdir	call site: 01669	gen_llc
11	84	pcap_parse	call site: 00084	pcap__create_buffer

Runtime coverage analysis

Covered functions

326

Functions that are reachable but not covered

80

Reachable functions

370

Percentage of reachable functions covered

78.38%

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	10
gencode.c	211
build/scanner.c	24
build/grammar.c	2
missing/strlcpy.c	1
scanner.l	2
nametoaddr.c	16
extract.h	2
build/grammar.y	4
optimize.c	48
bpf_filter.c	4

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_activate_linux	/src/libpcap/pcap-linux.c	1	['N/A']	8	0	343	45	15	56	0	293	262
pcap_ng_next_packet	/src/libpcap/sf-pcapng.c	3	['N/A', 'N/A', 'N/A']	6	0	734	70	19	38	0	216	189
pcap_lookupdev	/src/libpcap/pcap.c	1	['N/A']	9	0	74	14	6	41	0	185	137
pcap_read_linux_mmap_v3	/src/libpcap/pcap-linux.c	4	['N/A', 'int', 'N/A', 'N/A']	6	0	522	77	28	26	0	181	92
pcap_open_live	/src/libpcap/pcap.c	5	['N/A', 'int', 'int', 'int', 'N/A']	8	0	183	29	12	30	0	137	91
netfilter_activate	/src/libpcap/pcap-netfilter-linux.c	1	['N/A']	5	0	598	89	35	28	0	119	80
pcap_setfilter_linux	/src/libpcap/pcap-linux.c	2	['N/A', 'N/A']	5	0	344	65	21	23	0	167	68
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	739	112	37	23	0	147	41
pcap_check_header	/src/libpcap/sf-pcap.c	5	['N/A', 'N/A', 'int', 'N/A', 'N/A']	6	0	523	75	24	16	0	71	35

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

Functions statically reachable by fuzzers

452 / 598

Cyclomatic complexity statically reachable by fuzzers

3450 / 4014

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', 'pcap_next_ex', '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_scode', 'gen_mtp2type_abbrev', 'gen_atmmulti_abbrev', 'gen_byteop', 'gen_vlan_vid_test', 'sdup', 'pcap_lex', 'gen_mcode', 'gen_llc_u_subtype']

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_both', 'fuzz_pcap']
yy_get_next_buffer	90	19	21.11%	['fuzz_both', 'fuzz_filter']
gen_scode	115	61	53.04%	['fuzz_both', 'fuzz_filter']
gen_atmmulti_abbrev	48	20	41.66%	['fuzz_both', 'fuzz_filter']

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

Directories in report

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