High level conclusions

Fuzzers reach 56.77% code coverage.

Fuzzers reach 74.95% of cyclomatic complexity.

Fuzzers reach 70.33% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

83 / 118

Cyclomatic complexity statically reachable by fuzzers

383 / 511

Runtime code coverage of functions

67 / 118

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: libidn_toascii_fuzzer

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	8.24%
gold	[1:9]	0	0.0%
yellow	[10:29]	1	1.03%
greenyellow	[30:49]	3	3.09%
lawngreen	50+	85	87.6%
All colors	97	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	85	stringprep_convert	call site: 00085
1	17	idna_to_ascii_4i	call site: 00017
1	27	g_utf8_to_ucs4_fast	call site: 00027	g_utf8_next_char
1	64	idna_to_ascii_4z	call site: 00064
1	69	LLVMFuzzerTestOneInput	call site: 00069

Runtime coverage analysis

Covered functions

38

Functions that are reachable but not covered

22

Reachable functions

41

Percentage of reachable functions covered

46.34%

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/libidn_toascii_fuzzer.c	10
lib/idna.c	18
lib/nfkc.c	10
lib/punycode.c	4
lib/idn-free.c	1
lib/toutf8.c	7

Fuzzer: libidn_tounicode_fuzzer

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	14	9.85%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	128	90.1%
All colors	142	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	122	stringprep_convert	call site: 00122
2	35	punycode_decode	call site: 00035	flagged
2	94	idna_to_unicode_4z4z	call site: 00094
1	17	idna_to_unicode_internal	call site: 00017
1	30	punycode_decode	call site: 00030	flagged
1	46	idna_to_ascii_4i	call site: 00046
1	56	g_utf8_to_ucs4_fast	call site: 00056	g_utf8_next_char
1	90	idna_to_unicode_4z4z	call site: 00090
1	99	LLVMFuzzerTestOneInput	call site: 00099

Runtime coverage analysis

Covered functions

46

Functions that are reachable but not covered

23

Reachable functions

51

Percentage of reachable functions covered

54.9%

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/libidn_tounicode_fuzzer.c	12
lib/idna.c	24
lib/nfkc.c	10
lib/punycode.c	8
lib/idn-free.c	1
lib/toutf8.c	7

Fuzzer: libidn_stringprep_fuzzer

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	9	5.23%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	163	94.7%
All colors	172	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	130	stringprep_convert	call site: 00130
1	24	g_utf8_to_ucs4_fast	call site: 00024	g_utf8_next_char
1	28	stringprep	call site: 00028
1	95	LLVMFuzzerTestOneInput	call site: 00095
1	113	LLVMFuzzerTestOneInput	call site: 00113	tld_get_table
1	138	LLVMFuzzerTestOneInput	call site: 00138

Runtime coverage analysis

Covered functions

57

Functions that are reachable but not covered

28

Reachable functions

80

Percentage of reachable functions covered

65.0%

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/libidn_stringprep_fuzzer.c	21
lib/version.c	1
lib/stringprep.c	19
lib/nfkc.c	27
lib/idn-free.c	1
lib/pr29.c	7
lib/tld.c	15
lib/toutf8.c	7

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

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

Functions statically reachable by fuzzers

83 / 118

Cyclomatic complexity statically reachable by fuzzers

383 / 511

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/libidn_toascii_fuzzer.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=['stringprep_convert', 'idna_to_ascii_4i', 'g_utf8_to_ucs4_fast', 'idna_to_ascii_4z', 'LLVMFuzzerTestOneInput']

fuzz/libidn_tounicode_fuzzer.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=['stringprep_convert', 'punycode_decode', 'idna_to_unicode_4z4z', 'idna_to_unicode_internal', 'idna_to_ascii_4i', 'g_utf8_to_ucs4_fast', 'LLVMFuzzerTestOneInput']

fuzz/libidn_stringprep_fuzzer.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=['stringprep_convert', 'g_utf8_to_ucs4_fast', 'stringprep', 'LLVMFuzzerTestOneInput']

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
str_cd_iconv	104	54	51.92%

New fuzzers

The below fuzzers are templates and suggestions for how to target the set of optimal functions above

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/libidn/fuzz/libidn_tounicode_fuzzer.c	['libidn_tounicode_fuzzer']	['libidn_tounicode_fuzzer']
/src/libidn/examples/example.c	[]	[]
/src/libidn/tests/tst_pr29.c	[]	[]
/src/libidn/lib/stringprep.c	['libidn_stringprep_fuzzer']	['libidn_stringprep_fuzzer']
/src/libidn/fuzz/libidn_stringprep_fuzzer.c	['libidn_stringprep_fuzzer']	['libidn_stringprep_fuzzer']
/src/libidn/lib/strerror-pr29.c	[]	[]
/src/libidn/lib/pr29.c	['libidn_stringprep_fuzzer']	['libidn_stringprep_fuzzer']
/src/libidn/lib/nfkc.c	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']
/src/libidn/lib/strerror-stringprep.c	[]	[]
/src/libidn/tests/tst_symbols.c	[]	[]
/src/libidn/fuzz/libidn_toascii_fuzzer.c	['libidn_toascii_fuzzer']	['libidn_toascii_fuzzer']
/src/libidn/lib/profiles.c	[]	[]
/src/libidn/contrib/java/IDNA.c	[]	[]
/src/libidn/lib/idn-free.c	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']
/src/libidn/fuzz/main.c	[]	[]
/src/libidn/tests/utils.c	[]	[]
/src/libidn/lib/version.c	['libidn_stringprep_fuzzer']	['libidn_stringprep_fuzzer']
/src/libidn/lib/toutf8.c	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer', 'libidn_stringprep_fuzzer']
/src/libidn/lib/strerror-punycode.c	[]	[]
/src/libidn/lib/stringprep.h	[]	[]
/src/libidn/lib/idna.c	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer']	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer']
/src/libidn/lib/punycode.c	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer']	['libidn_toascii_fuzzer', 'libidn_tounicode_fuzzer']
/src/libidn/lib/strerror-tld.c	[]	[]
/src/libidn/src/idn.c	[]	[]
/src/libidn/contrib/idn-python/idn.c	[]	[]
/src/libidn/lib/strerror-idna.c	[]	[]
/src/libidn/lib/tld.c	['libidn_stringprep_fuzzer']	['libidn_stringprep_fuzzer']
/src/libidn/examples/example2.c	[]	[]

Directories in report

Directory
/src/libidn/contrib/idn-python/
/src/libidn/tests/
/src/libidn/examples/
/src/libidn/src/
/src/libidn/fuzz/
/src/libidn/contrib/java/
/src/libidn/lib/

This section shows a list of 3rd party function calls and their relative coverage information. By static analysis of the target project code, all of the 3rd party function call and their caller information, including the source file and line number that initiate the call are captured. The caller source code file and line number are shown in column 2 while column 1 is the function name of the 3rd party function call. Each occurrent of the 3rd party function call will occuply a separate row. Column 3 of each row indicate if the 3rd party call in the source file line is unreachable. Column 4 lists all fuzzers that have covered that particular system call in that specific location (source file and line)during their dynamic fuzzing.

Function in each files in report

Target sink	Callsite location	Reached by fuzzer	Covered by Fuzzers