High level conclusions

Fuzzers reach 99.55% of cyclomatic complexity.

Fuzzers reach 96.96% of all functions.

Fuzzers reach 95.45% code coverage.

Reachability and coverage overview

Functions statically reachable by fuzzers

64 / 66

Cyclomatic complexity statically reachable by fuzzers

1107 / 1112

Runtime code coverage of functions

63 / 66

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: bzip2_decompress_target

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	24.3%
gold	[1:9]	0	0.0%
yellow	[10:29]	1	2.70%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	27	72.9%
All colors	37	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
7	25	BZ2_decompress	call site: 00025	BZ2_bz__AssertH__fail
1	16	BZ2_bzDecompress	call site: 00016	fprintf
1	19	BZ2_bzDecompress	call site: 00019	fprintf

Runtime coverage analysis

Covered functions

14

Functions that are reachable but not covered

4

Reachable functions

16

Percentage of reachable functions covered

75.0%

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
bzip2_decompress_target.c	1
bzip2/bzlib.c	10
bzip2/decompress.c	2
bzip2/huffman.c	1

Fuzzer: bzip2_compress_target

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	44	27.1%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	118	72.8%
All colors	162	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
5	131	BZ2_bzDecompress	call site: 00131	BZ2_indexIntoF
4	25	fallbackQSort3	call site: 00025	BZ2_bzlibVersion
4	73	sendMTFValues	call site: 00073	fprintf
3	47	mainSort	call site: 00047	fprintf
3	151	BZ2_decompress	call site: 00151	BZ2_bz__AssertH__fail
3	155	BZ2_bzBuffToBuffDecompress	call site: 00155	BZ2_bzDecompressEnd
2	21	BZ2_blockSort	call site: 00021	fprintf
2	30	fallbackQSort3	call site: 00030	fprintf
2	119	handle_compress	call site: 00119	handle_compress
2	124	BZ2_bzBuffToBuffCompress	call site: 00124	BZ2_bzCompressEnd
1	6	BZ2_bzBuffToBuffCompress	call site: 00006	handle_compress
1	10	handle_compress	call site: 00010	isempty_RL

Runtime coverage analysis

Covered functions

46

Functions that are reachable but not covered

6

Reachable functions

50

Percentage of reachable functions covered

88.0%

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
bzip2_compress_target.c	1
bzip2/bzlib.c	22
bzip2/compress.c	9
bzip2/blocksort.c	9
bzip2/huffman.c	3
bzip2/decompress.c	2

Fuzzer: bzip2_fd

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	70	32.8%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	143	67.1%
All colors	213	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
14	174	BZ2_bzRead	call site: 00174	unRLE_obuf_to_output_SMALL
9	189	BZ2_bzDecompress	call site: 00189	BZ2_hbCreateDecodeTables
4	7	LLVMFuzzerTestOneInput	call site: 00007	perror
4	41	fallbackQSort3	call site: 00041	BZ2_bzlibVersion
4	89	sendMTFValues	call site: 00089	fprintf
3	63	mainSort	call site: 00063	fprintf
3	170	myfeof	call site: 00170	ungetc
3	201	fuzzer_read_data	call site: 00201	BZ2_bzWriteClose
2	1	LLVMFuzzerTestOneInput	call site: 00001	perror
2	4	LLVMFuzzerTestOneInput	call site: 00004	perror
2	37	BZ2_blockSort	call site: 00037	fprintf
2	46	fallbackQSort3	call site: 00046	fprintf

Runtime coverage analysis

Covered functions

56

Functions that are reachable but not covered

28

Reachable functions

82

Percentage of reachable functions covered

65.85%

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
bzip2_fd.c	3
bzip2/bzlib.c	36
bzip2/compress.c	9
bzip2/blocksort.c	9
bzip2/huffman.c	3
bzip2/decompress.c	2

Fuzzer: bzip2_filename

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	56	27.4%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	148	72.5%
All colors	204	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
11	171	BZ2_bzRead	call site: 00171	unRLE_obuf_to_output_SMALL
5	190	BZ2_decompress	call site: 00190	BZ2_bz__AssertH__fail
4	39	fallbackQSort3	call site: 00039	BZ2_bzlibVersion
4	87	sendMTFValues	call site: 00087	fprintf
3	7	LLVMFuzzerTestOneInput	call site: 00007	perror
3	61	mainSort	call site: 00061	fprintf
2	1	LLVMFuzzerTestOneInput	call site: 00001	perror
2	4	LLVMFuzzerTestOneInput	call site: 00004	perror
2	35	BZ2_blockSort	call site: 00035	fprintf
2	44	fallbackQSort3	call site: 00044	fprintf
2	133	handle_compress	call site: 00133	handle_compress
2	156	bzopen_or_bzdopen	call site: 00156	BZ2_bzWriteOpen

Runtime coverage analysis

Covered functions

55

Functions that are reachable but not covered

23

Reachable functions

76

Percentage of reachable functions covered

69.74%

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
bzip2_filename.c	3
bzip2/bzlib.c	30
bzip2/compress.c	9
bzip2/blocksort.c	9
bzip2/huffman.c	3
bzip2/decompress.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

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

Functions statically reachable by fuzzers

64 / 66

Cyclomatic complexity statically reachable by fuzzers

1107 / 1112

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.

bzip2_decompress_target.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=['BZ2_decompress', 'BZ2_bzDecompress']

bzip2_compress_target.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=['BZ2_bzDecompress', 'fallbackQSort3', 'sendMTFValues', 'mainSort', 'BZ2_decompress', 'BZ2_bzBuffToBuffDecompress', 'BZ2_blockSort', 'handle_compress', 'BZ2_bzBuffToBuffCompress']

bzip2_fd.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=['BZ2_bzRead', 'BZ2_bzDecompress', 'LLVMFuzzerTestOneInput', 'fallbackQSort3', 'sendMTFValues', 'mainSort', 'myfeof', 'fuzzer_read_data']

bzip2_filename.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=['BZ2_bzRead', 'BZ2_decompress', 'fallbackQSort3', 'sendMTFValues', 'LLVMFuzzerTestOneInput', 'mainSort', 'BZ2_blockSort']

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

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/bzip2/compress.c	['bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']	['bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']
/src/bzip2_decompress_target.c	['bzip2_decompress_target']	['bzip2_decompress_target']
/src/bzip2/huffman.c	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']
/src/bzip2_fd.c	['bzip2_fd']	['bzip2_fd']
/src/bzip2/blocksort.c	['bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']	['bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']
/src/bzip2/bzlib.c	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']
/src/bzip2_filename.c	['bzip2_filename']	['bzip2_filename']
/src/bzip2_compress_target.c	['bzip2_compress_target']	['bzip2_compress_target']
/src/bzip2/decompress.c	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']	['bzip2_decompress_target', 'bzip2_compress_target', 'bzip2_fd', 'bzip2_filename']

Directories in report

Directory
/src/bzip2/
/src/