High level conclusions

Fuzzers reach 50.91% code coverage.

Fuzzers reach 5.978% of cyclomatic complexity.

Fuzzers reach 3.663% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

10 / 273

Cyclomatic complexity statically reachable by fuzzers

33 / 552

Runtime code coverage of functions

139 / 273

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: structured_fuzz_reader

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	290	64.8%
gold	[1:9]	9	2.01%
yellow	[10:29]	17	3.80%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	131	29.3%
All colors	447	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
63	228	ZipArchive::by_index_with_optional_password	call site: 00228	ZipCryptoReader::validate
40	2	fuzzed_extract	call site: 00002	CentralDirectoryEnd::parse
37	89	ZipArchive::get_directory_counts	call site: 00089	central_header_to_zip_file
23	419	fuzzed_extract	call site: 00419	ZipArchive::new
16	163	parse_extra_field	call site: 00163	CompressionMethod::from_u16
15	69	ZipArchive::get_directory_counts	call site: 00069	Zip64File::seek
14	182	parse_extra_field	call site: 00182
10	212	ZipArchive::by_index_with_optional_password	call site: 00212	Zip64File::seek
9	131	AtomicU64::load	call site: 00131	CentralDirectoryEnd::record_too_small
8	316	ZipFileData::file_name_sanitized	call site: 00316
7	48	ZipArchive::get_directory_counts	call site: 00048
7	142	to_char	call site: 00142	System::from_u8

Runtime coverage analysis

Covered functions

732

Functions that are reachable but not covered

12

Reachable functions

38

Percentage of reachable functions covered

68.42%

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
fuzz/fuzz_targets/structured_fuzz_reader.rs	33
tests/zip64_large.rs	24
src/spec.rs	15
src/read.rs	68
src/types.rs	20
src/cp437.rs	7
src/compression.rs	1
fuzz/fuzz_targets/fuzz_read.rs	2
src/zipcrypto.rs	17
src/aes.rs	4
src/write.rs	6
tests/zip_comment_garbage.rs	5

Fuzzer: roundtrip

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	698	79.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	4	0.45%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	174	19.8%
All colors	876	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
123	661	ZipWriter::end_extra_data	call site: 00661	ZipWriter::start_file
83	479	ZipArchive::get_directory_counts	call site: 00479	central_header_to_zip_file
69	198	zip::result::ZipResult::version_needed	call site: 00198	CentralDirectoryEnd::write
54	312	AtomicU64::new	call site: 00312	write_local_file_header
53	804	ZipArchive::by_index_with_optional_password	call site: 00804	ZipCryptoReader::validate
41	418	build_zip	call site: 00418	CentralDirectoryEnd::parse
36	610	ZipArchive::by_index_with_optional_password	call site: 00610	ZipWriter::add_directory
23	565	parse_extra_field	call site: 00565	Zip64File::seek
22	275	ZipWriter::finish_file	call site: 00275	Zip64File::seek
19	178	ZipWriter::finish_file	call site: 00178	ZipWriter::finalize
18	101	GenericZipWriter::switch_to	call site: 00101
18	589	parse_extra_field	call site: 00589

Runtime coverage analysis

Covered functions

1163

Functions that are reachable but not covered

20

Reachable functions

38

Percentage of reachable functions covered

47.37%

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
fuzz/fuzz_targets/roundtrip.rs	32
tests/zip64_large.rs	27
src/types.rs	20
src/write.rs	107
src/read.rs	60
src/zipcrypto.rs	20
src/spec.rs	18
src/cp437.rs	7
src/compression.rs	1
fuzz/fuzz_targets/fuzz_read.rs	9
tests/end_to_end.rs	28
src/aes.rs	4

Fuzzer: fuzz_zip

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	190	84.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	36	15.9%
All colors	226	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
44	181	parse_extra_field	call site: 00181	ZipArchive::new
41	0	EP	call site: 00000	CentralDirectoryEnd::parse
37	88	ZipArchive::get_directory_counts	call site: 00088	central_header_to_zip_file
23	157	parse_extra_field	call site: 00157	Zip64File::seek
15	68	ZipArchive::get_directory_counts	call site: 00068	Zip64File::seek
10	141	to_char	call site: 00141	System::from_u8
9	130	AtomicU64::load	call site: 00130	CentralDirectoryEnd::record_too_small
7	47	ZipArchive::get_directory_counts	call site: 00047
1	44	ZipArchive::get_directory_counts	call site: 00044
1	55	ZipArchive::get_directory_counts	call site: 00055
1	127	atomic::AtomicU64::new	call site: 00127
1	153	AtomicU64::new	call site: 00153	parse_extra_field

Runtime coverage analysis

Covered functions

1498

Functions that are reachable but not covered

1

Reachable functions

6

Percentage of reachable functions covered

83.33%

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
fuzz/fuzz_targets/fuzz_zip.rs	6
tests/zip64_large.rs	21
src/spec.rs	15
src/read.rs	37
src/types.rs	3
src/cp437.rs	7
src/compression.rs	1
tests/zip_comment_garbage.rs	5

Fuzzer: fuzz_read

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	624	78.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	6	0.75%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	163	20.5%
All colors	793	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
80	690	ZipArchive::by_name	call site: 00690	ZipWriter::raw_copy_file
69	467	zip::result::ZipResult::version_needed	call site: 00467	CentralDirectoryEnd::write
63	223	ZipArchive::by_index_with_optional_password	call site: 00223	ZipCryptoReader::validate
60	569	ZipWriter::finish_file	call site: 00569	write_local_file_header
43	0	EP	call site: 00000	CentralDirectoryEnd::parse
37	90	ZipArchive::get_directory_counts	call site: 00090	central_header_to_zip_file
27	630	FileOptions::unix_permissions	call site: 00630	ZipWriter::start_file
23	159	parse_extra_field	call site: 00159	Zip64File::seek
22	544	ZipWriter::finish_file	call site: 00544	Zip64File::seek
21	297	ZipArchive::by_index	call site: 00297	ZipWriter::add_directory
19	447	ZipWriter::finish_file	call site: 00447	ZipWriter::finalize
19	773	zip::result::ZipResult::by_name	call site: 00773	ZipWriter::raw_copy_file_rename

Runtime coverage analysis

Covered functions

1498

Functions that are reachable but not covered

5

Reachable functions

10

Percentage of reachable functions covered

50.0%

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.

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
fuzz/fuzz_targets/fuzz_read.rs	10
tests/zip64_large.rs	27
src/spec.rs	18
src/read.rs	60
src/types.rs	20
src/cp437.rs	7
src/compression.rs	1
src/zipcrypto.rs	20
src/aes.rs	4
tests/end_to_end.rs	28
src/write.rs	102

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

10 / 273

Cyclomatic complexity statically reachable by fuzzers

33 / 552

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/fuzz_targets/structured_fuzz_reader.rs

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=['ZipArchive::by_index_with_optional_password', 'fuzzed_extract', 'ZipArchive::get_directory_counts', 'parse_extra_field', 'AtomicU64::load', 'ZipFileData::file_name_sanitized']

fuzz/fuzz_targets/roundtrip.rs

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=['ZipWriter::end_extra_data', 'ZipArchive::get_directory_counts', 'zip::result::ZipResult::version_needed', 'AtomicU64::new', 'ZipArchive::by_index_with_optional_password', 'build_zip', 'parse_extra_field', 'ZipWriter::finish_file']

fuzz/fuzz_targets/fuzz_zip.rs

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=['parse_extra_field', 'ZipArchive::get_directory_counts', 'to_char', 'AtomicU64::load']

fuzz/fuzz_targets/fuzz_read.rs

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=['ZipArchive::by_name', 'zip::result::ZipResult::version_needed', 'ZipArchive::by_index_with_optional_password', 'ZipWriter::finish_file', 'ZipArchive::get_directory_counts', 'FileOptions::unix_permissions', 'parse_extra_field', 'ZipArchive::by_index']

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
miniz_oxide::inflate::core::decode_huffman_code::miniz_oxide::inflate::core::decompress::{closure:#9}	67	34	50.74%
ERR_getErrorString	44	13	29.54%
XXH_INLINE_XXH64_update	38	20	52.63%
HUF_decompress4X2_usingDTable_internal_body	76	33	43.42%
ZSTD_decompressMultiFrame	76	33	43.42%
HUF_decompress4X2_usingDTable	74	33	44.59%
ZBUFF_decompressContinue	139	75	53.95%
HUFv05_readDTableX2	33	13	39.39%
HUFv06_decompress4X2_usingDTable	72	32	44.44%
ZSTDv06_decodeLiteralsBlock	113	54	47.78%
HUFv07_readStats	53	29	54.71%
HUFv07_readDTableX2	36	11	30.55%
ZSTDv07_decodeLiteralsBlock	114	41	35.96%
zip::read::parse_extra_field	54	29	53.70%
zip::read::make_crypto_reader	32	16	50.0%
ZSTD_cParam_getBounds	168	10	5.952%
ZSTD_CCtxParams_setParameter	185	15	8.108%
ZSTD_adjustCParams_internal	58	23	39.65%
ZSTD_buildSeqStore	131	64	48.85%
ZSTD_compressBlock_splitBlock_internal	62	31	50.0%
ZSTD_compressBlock_fast	32	15	46.87%
ZSTD_ldm_blockCompress	45	17	37.77%
ZSTD_rescaleFreqs	97	52	53.60%
zip::read::zip_archive::ZipArchivestd::io::cursor::Cursoralloc::vec::Vecu8::get_directory_counts	56	23	41.07%

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/zip/src/read/stream.rs	[]	[]
/src/zip/benches/read_entry.rs	[]	[]
/src/zip/examples/write_dir.rs	[]	[]
/src/zip/src/types.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']
/src/zip/fuzz/fuzz_targets/fuzz_zip.rs	['fuzz_zip']	[]
/src/zip/src/crc32.rs	[]	[]
/src/zip/src/aes.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']
/src/zip/tests/issue_234.rs	[]	[]
/src/zip/src/zipcrypto.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']
/src/zip/tests/zip_crypto.rs	[]	[]
/src/zip/src/result.rs	[]	[]
/src/zip/src/write.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']
/src/zip/src/compression.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']
/src/zip/fuzz/fuzz_targets/roundtrip.rs	['roundtrip']	['roundtrip']
/src/zip/tests/aes_encryption.rs	[]	[]
/src/zip/src/cp437.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']
/src/zip/benches/read_metadata.rs	[]	[]
/src/zip/src/read.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']
/src/zip/tests/invalid_date.rs	[]	[]
/src/zip/tests/zip_comment_garbage.rs	['structured_fuzz_reader', 'fuzz_zip']	[]
/src/zip/tests/end_to_end.rs	['roundtrip', 'fuzz_read']	[]
/src/zip/fuzz/fuzz_targets/structured_fuzz_reader.rs	['structured_fuzz_reader']	['structured_fuzz_reader']
/src/zip/tests/zip64_large.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']
/src/zip/src/aes_ctr.rs	[]	[]
/src/zip/fuzz/fuzz_targets/fuzz_read.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_read']	[]
/src/zip/src/spec.rs	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']	['structured_fuzz_reader', 'roundtrip', 'fuzz_zip', 'fuzz_read']

Directories in report

Directory
/src/zip/src/read/
/src/zip/tests/
/src/zip/src/
/src/zip/examples/
/src/zip/benches/
/src/zip/fuzz/fuzz_targets/

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