Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues
Project coverage
Per-fuzzer coverage

Table of contents

Project overview: bzip2
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: bzip2_decompress_target
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Fuzzer: bzip2_compress_target
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Runtime coverage analysis
Complex functions with low coverage
Files and Directories in report
Files in report
Directories in report
Metadata section
Report generation date: 2022-10-17

Project overview: bzip2

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
60.49%
49/81
Cyclomatic complexity statically reachable by fuzzers
77.5%
885/1142
Functions covered at runtime
46

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
bzip2_decompress_target bzip2_decompress_target.c 16 63 5 4 1240 424 bzip2_decompress_target.c
bzip2_compress_target bzip2_compress_target.c 49 32 9 6 2520 885 bzip2_compress_target.c

Project functions overview

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 Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Fuzzer details

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

Full calltree

Call tree overview bitmap:

The distribution of callsites in terms of coloring is
Color Runtime hitcount Callsite count Percentage
red 0 9 23.0%
gold [1:9] 0 0.0%
yellow [10:29] 1 2.56%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 29 74.3%
All colors 39 100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity Unique Reachable Complexities Unique Reachable Functions All non-covered Complexity All Reachable Complexity Function Name Function Callsite Blocked Branch
0 0 None 0 369 BZ2_bzDecompress call site /src/bzip2/bzlib.c:826
0 0 None 0 19 BZ2_decompress call site /src/bzip2/decompress.c:238
0 0 None 0 0 BZ2_bzDecompress call site /src/bzip2/bzlib.c:844
0 0 None 0 0 BZ2_bzBuffToBuffDecompress call site /src/bzip2/bzlib.c:1310
0 0 None 0 0 unRLE_obuf_to_output_FAST call site /src/bzip2/bzlib.c:666
0 0 None 0 0 BZ2_decompress call site /src/bzip2/decompress.c:512
0 0 None 0 0 BZ2_decompress call site /src/bzip2/decompress.c:519

Runtime coverage analysis

Covered functions
14
Functions that are reachable but not covered
3
Reachable functions
16
Percentage of reachable functions covered
81.25%
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 12
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

Full calltree

Call tree overview bitmap:

The distribution of callsites in terms of coloring is
Color Runtime hitcount Callsite count Percentage
red 0 43 26.2%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 121 73.7%
All colors 164 100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity Unique Reachable Complexities Unique Reachable Functions All non-covered Complexity All Reachable Complexity Function Name Function Callsite Blocked Branch
0 0 None 49 210 sendMTFValues call site /src/bzip2/compress.c:261
0 0 None 42 203 sendMTFValues call site /src/bzip2/compress.c:302
0 0 None 42 203 sendMTFValues call site /src/bzip2/compress.c:436
0 0 None 21 101 mainSort call site /src/bzip2/blocksort.c:893
0 0 None 14 132 sendMTFValues call site /src/bzip2/compress.c:513
0 0 None 14 124 sendMTFValues call site /src/bzip2/compress.c:525
0 0 None 14 116 sendMTFValues call site /src/bzip2/compress.c:541
0 0 None 7 80 BZ2_blockSort call site /src/bzip2/blocksort.c:1069
0 0 None 7 80 BZ2_blockSort call site /src/bzip2/blocksort.c:1076
0 0 None 7 43 fallbackSort call site /src/bzip2/blocksort.c:229
0 0 None 7 43 fallbackSort call site /src/bzip2/blocksort.c:263
0 0 None 7 43 fallbackSort call site /src/bzip2/blocksort.c:308

Runtime coverage analysis

Covered functions
46
Functions that are reachable but not covered
4
Reachable functions
49
Percentage of reachable functions covered
91.84%
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 24
bzip2/compress.c 9
bzip2/blocksort.c 9
bzip2/huffman.c 3
bzip2/decompress.c 2

Analyses and suggestions

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
BZ2_bzdopen /src/bzip2/bzlib.c 2 ['int ', 'char *'] 4 0 20 3 2 17 0 125 84
BZ2_bzclose /src/bzip2/bzlib.c 1 ['char *'] 10 0 82 16 7 41 0 506 62
BZ2_bzread /src/bzip2/bzlib.c 3 ['char *', 'char *', 'int '] 5 0 67 11 5 16 0 440 53

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

Functions statically reachable by fuzzers
88.89%
72/81
Cyclomatic complexity statically reachable by fuzzers
94.92%
1084 / 1142

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 Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Runtime coverage analysis

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
mainGtU 117 44 37.60% ['bzip2_compress_target']
BZ2_bzCompress 57 30 52.63% ['bzip2_compress_target']
copy_input_until_stop 40 19 47.5% ['bzip2_compress_target']

Files and Directories in report

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

Directories in report

Directory
/src/
/src/bzip2/

Metadata section

This sections shows the raw data that is used to produce this report. This is mainly used for further processing and developer debugging.

Fuzzer Calltree file Program data file Coverage file
bzip2_decompress_target fuzzerLogFile-0-aNpAxBV4u7.data fuzzerLogFile-0-aNpAxBV4u7.data.yaml bzip2_decompress_target.covreport
bzip2_compress_target fuzzerLogFile-0-k7q0wiLa7a.data fuzzerLogFile-0-k7q0wiLa7a.data.yaml bzip2_compress_target.covreport