Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues

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 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 details

Fuzzer: fuzz_decode_alone

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 5 25.0%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 15 75.0%
All colors 20 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
2 11 lzma_end call site: 00011 fprintf
2 16 lzma_code call site: 00016 fprintf
1 6 lzma_alone_decoder_init call site: 00006 lzma_free

Runtime coverage analysis

Covered functions
37
Functions that are reachable but not covered
3
Reachable functions
13
Percentage of reachable functions covered
76.92%
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
/src/xz/tests/ossfuzz/fuzz_decode_alone.c 1
/src/xz/src/liblzma/common/alone_decoder.c 2
/src/xz/src/liblzma/common/common.c 6
/src/xz/tests/ossfuzz/./fuzz_common.h 1

Fuzzer: fuzz_encode_stream

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 24 27.9%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 62 72.0%
All colors 86 100

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 33 index_tree_append call site: 00033 __assert_fail
3 81 fuzz_code call site: 00081 __assert_fail
2 2 LLVMFuzzerTestOneInput call site: 00002 fprintf
2 16 index_tree_end call site: 00016 index_tree_node_end
2 77 lzma_end call site: 00077 fprintf
1 0 EP call site: 00000 fprintf
1 10 stream_encoder_init call site: 00010 lzma_free
1 30 index_stream_init call site: 00030 lzma_free
1 41 lzma_stream_header_encode call site: 00041 stream_encoder_update
1 45 lzma_filters_copy call site: 00045 lzma_free
1 48 block_encoder_init call site: 00048 lzma_vli_size
1 50 lzma_vli_size call site: 00050 lzma_vli_size

Runtime coverage analysis

Covered functions
176
Functions that are reachable but not covered
6
Reachable functions
47
Percentage of reachable functions covered
87.23%
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
/src/xz/tests/ossfuzz/fuzz_encode_stream.c 1
/src/xz/src/liblzma/lzma/lzma_encoder_presets.c 1
/src/xz/src/liblzma/common/stream_encoder.c 4
/src/xz/src/liblzma/common/common.c 7
/src/xz/src/liblzma/common/index.c 9
/src/xz/src/liblzma/../../src/common/tuklib_integer.h 3
/src/xz/src/liblzma/common/stream_flags_encoder.c 2
/src/xz/src/liblzma/check/crc32_fast.c 1
/src/xz/src/liblzma/common/filter_common.c 4
/src/xz/src/liblzma/common/block_header_encoder.c 1
/src/xz/src/liblzma/common/vli_size.c 1
/src/xz/src/liblzma/common/filter_flags_encoder.c 1
/src/xz/src/liblzma/common/filter_encoder.c 4
/src/xz/src/liblzma/common/block_encoder.c 1
/src/xz/src/liblzma/check/check.c 2
/src/xz/src/liblzma/check/sha256.c 1
/src/xz/tests/ossfuzz/./fuzz_common.h 1

Fuzzer: fuzz_decode_stream

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 5 19.2%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 21 80.7%
All colors 26 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
2 17 lzma_end call site: 00017 fprintf
2 22 lzma_code call site: 00022 fprintf
1 6 lzma_stream_decoder_init call site: 00006 lzma_free

Runtime coverage analysis

Covered functions
141
Functions that are reachable but not covered
3
Reachable functions
17
Percentage of reachable functions covered
82.35%
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
/src/xz/tests/ossfuzz/fuzz_decode_stream.c 1
/src/xz/src/liblzma/common/stream_decoder.c 3
/src/xz/src/liblzma/common/common.c 6
/src/xz/src/liblzma/common/index_hash.c 1
/src/xz/src/liblzma/check/check.c 1
/src/xz/src/liblzma/check/sha256.c 1
/src/xz/tests/ossfuzz/./fuzz_common.h 1

Fuzzer: fuzz_decode_stream_mt

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 20.2%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 55 79.7%
All colors 69 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
2 9 stream_decoder_mt_init call site: 00009 lzma_free
2 17 mythread_cond_init call site: 00017 mythread_mutex_destroy
2 60 lzma_end call site: 00060 fprintf
2 65 lzma_code call site: 00065 fprintf
1 6 stream_decoder_mt_init call site: 00006 lzma_free
1 21 mythread_mutex_destroy call site: 00021 lzma_free
1 23 stream_decoder_mt_init call site: 00023 __assert_fail
1 36 threads_end call site: 00036 pthread_join
1 39 stream_decoder_mt_init call site: 00039 move_head_to_cache
1 50 move_head_to_cache call site: 00050 free_one_cached_buffer

Runtime coverage analysis

Covered functions
176
Functions that are reachable but not covered
14
Reachable functions
42
Percentage of reachable functions covered
66.67%
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
/src/xz/tests/ossfuzz/fuzz_decode_stream_mt.c 1
/src/xz/src/liblzma/common/stream_decoder_mt.c 4
/src/xz/src/liblzma/common/common.c 6
/src/xz/src/liblzma/../../src/common/mythread.h 7
/src/xz/src/liblzma/common/filter_common.c 1
/src/xz/src/liblzma/common/outqueue.c 4
/src/xz/src/liblzma/common/outqueue.h 1
/src/xz/src/liblzma/common/index_hash.c 1
/src/xz/src/liblzma/check/check.c 1
/src/xz/src/liblzma/check/sha256.c 1
/src/xz/tests/ossfuzz/./fuzz_common.h 1

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
stream_decode_mt /src/xz/src/liblzma/common/stream_decoder_mt.c 9 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t', 'N/A', 'N/A', 'size_t', 'int'] 6 0 1900 276 84 104 0 572 440
lzma2_encode /src/xz/src/liblzma/lzma/lzma2_encoder.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t'] 6 0 387 51 12 65 0 405 395
lzma_decode /src/xz/src/liblzma/lzma/lzma_decoder.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t'] 2 0 5344 689 129 8 0 154 152
stream_encode /src/xz/src/liblzma/common/stream_encoder.c 9 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t', 'N/A', 'N/A', 'size_t', 'int'] 7 0 396 53 14 44 0 232 87
lzma_lzma2_encoder_init /src/xz/src/liblzma/lzma/lzma2_encoder.c 3 ['N/A', 'N/A', 'N/A'] 7 0 21 3 2 25 0 136 68
lzma_index_buffer_encode /src/xz/src/liblzma/common/index_encoder.c 4 ['N/A', 'N/A', 'N/A', 'size_t'] 7 0 98 18 7 17 0 85 54
lzma_mf_bt4_find /src/xz/src/liblzma/lz/lz_encoder_mf.c 2 ['N/A', 'N/A'] 3 0 500 51 16 9 0 61 53
lzma_lzma_decoder_init /src/xz/src/liblzma/lzma/lzma_decoder.c 3 ['N/A', 'N/A', 'N/A'] 4 0 36 6 2 13 0 70 44

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

Functions statically reachable by fuzzers
56.0%
236 / 421
Cyclomatic complexity statically reachable by fuzzers
65.0%
1598 / 2443

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

Fuzz engine guidance

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.

/src/xz/tests/ossfuzz/fuzz_decode_alone.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=['lzma_end', 'lzma_code', 'lzma_alone_decoder_init']

/src/xz/tests/ossfuzz/fuzz_encode_stream.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=['index_tree_append', 'fuzz_code', 'LLVMFuzzerTestOneInput', 'index_tree_end', 'lzma_end', 'stream_encoder_init', 'index_stream_init', 'lzma_stream_header_encode', 'lzma_filters_copy']

/src/xz/tests/ossfuzz/fuzz_decode_stream.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=['lzma_end', 'lzma_code', 'lzma_stream_decoder_init']

/src/xz/tests/ossfuzz/fuzz_decode_stream_mt.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=['stream_decoder_mt_init', 'mythread_cond_init', 'lzma_end', 'lzma_code', 'mythread_mutex_destroy', 'threads_end', 'move_head_to_cache']

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/xz/src/liblzma/simple/simple_encoder.c [] []
/src/xz/src/liblzma/lzma/lzma_encoder_presets.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/../../src/common/mythread.h ['fuzz_decode_stream_mt'] []
/src/xz/src/liblzma/common/stream_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/vli_encoder.c [] []
/src/xz/src/liblzma/delta/delta_common.c [] []
/src/xz/src/liblzma/../../src/liblzma/rangecoder/range_decoder.h [] []
/src/xz/src/liblzma/lzma/fastpos.h [] []
/src/xz/src/liblzma/lzma/lzma_encoder.c [] []
/src/xz/src/liblzma/common/common.c ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt'] ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt']
/src/xz/src/liblzma/simple/simple_decoder.c [] []
/src/xz/src/liblzma/common/stream_decoder_mt.c ['fuzz_decode_stream_mt'] ['fuzz_decode_stream_mt']
/src/xz/src/liblzma/common/stream_flags_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/../../src/liblzma/lz/lz_encoder.h [] []
/src/xz/src/liblzma/simple/sparc.c [] []
/src/xz/src/liblzma/simple/riscv.c [] []
/src/xz/src/liblzma/common/index.h [] []
/src/xz/src/liblzma/lzma/lzma_decoder.c [] []
/src/xz/src/liblzma/common/filter_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/alone_decoder.c ['fuzz_decode_alone'] ['fuzz_decode_alone']
/src/xz/src/liblzma/lzma/lzma_common.h [] []
/src/xz/src/liblzma/lz/lz_encoder.c [] []
/src/xz/src/liblzma/delta/delta_decoder.c [] []
/src/xz/src/liblzma/common/index.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lzma/lzma2_decoder.c [] []
/src/xz/src/liblzma/../../src/liblzma/rangecoder/range_encoder.h [] []
/src/xz/src/liblzma/../../src/common/tuklib_integer.h ['fuzz_encode_stream'] []
/src/xz/src/liblzma/check/crc32_fast.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/usr/local/lib/clang/22/include/cpuid.h [] []
/src/xz/src/liblzma/delta/delta_encoder.c [] []
/src/xz/src/liblzma/common/block_header_decoder.c [] []
/src/xz/src/liblzma/common/stream_flags_common.h [] []
/src/xz/src/liblzma/common/index_hash.c ['fuzz_decode_stream', 'fuzz_decode_stream_mt'] ['fuzz_decode_stream', 'fuzz_decode_stream_mt']
/src/xz/src/liblzma/simple/ia64.c [] []
/src/xz/src/liblzma/lzma/lzma_encoder_optimum_fast.c [] []
/src/xz/src/liblzma/common/block_header_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lz/lz_decoder.c [] []
/src/xz/src/liblzma/check/crc64_fast.c [] []
/src/xz/src/liblzma/simple/arm.c [] []
/src/xz/src/liblzma/simple/simple_coder.c [] []
/src/xz/src/liblzma/common/filter_decoder.c [] []
/src/xz/src/liblzma/check/crc_x86_clmul.h [] []
/src/xz/tests/ossfuzz/fuzz_decode_alone.c ['fuzz_decode_alone'] ['fuzz_decode_alone']
/src/xz/src/liblzma/common/block_decoder.c [] []
/src/xz/src/liblzma/common/filter_flags_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/simple/x86.c [] []
/src/xz/src/liblzma/common/stream_flags_common.c [] []
/src/xz/src/liblzma/common/stream_decoder.c ['fuzz_decode_stream'] ['fuzz_decode_stream']
/src/xz/tests/ossfuzz/fuzz_decode_stream.c ['fuzz_decode_stream'] ['fuzz_decode_stream']
/src/xz/src/liblzma/common/filter_flags_decoder.c [] []
/src/xz/src/liblzma/common/vli_decoder.c [] []
/src/xz/src/liblzma/simple/arm64.c [] []
/src/xz/tests/ossfuzz/./fuzz_common.h ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt'] []
/src/xz/tests/ossfuzz/fuzz_decode_stream_mt.c ['fuzz_decode_stream_mt'] ['fuzz_decode_stream_mt']
/src/xz/src/liblzma/common/outqueue.c ['fuzz_decode_stream_mt'] ['fuzz_decode_stream_mt']
/src/xz/src/liblzma/../../src/liblzma/lz/lz_decoder.h [] []
/src/xz/src/liblzma/lzma/lzma2_encoder.c [] []
/src/xz/tests/ossfuzz/fuzz_encode_stream.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/simple/powerpc.c [] []
/src/xz/src/liblzma/lz/lz_encoder.h [] []
/src/xz/src/liblzma/common/block_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/../../src/liblzma/rangecoder/price.h [] []
/src/xz/src/liblzma/common/outqueue.h ['fuzz_decode_stream_mt'] ['fuzz_decode_stream_mt']
/src/xz/src/liblzma/check/check.c ['fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt'] ['fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt']
/src/xz/src/liblzma/lzma/lzma_encoder_optimum_normal.c [] []
/src/xz/src/liblzma/common/vli_size.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/index_encoder.c [] []
/src/xz/src/liblzma/simple/armthumb.c [] []
/src/xz/src/liblzma/lz/lz_encoder_mf.c [] []
/src/xz/src/liblzma/common/stream_flags_decoder.c [] []
/src/xz/src/liblzma/common/filter_common.c ['fuzz_encode_stream', 'fuzz_decode_stream_mt'] ['fuzz_encode_stream', 'fuzz_decode_stream_mt']
/src/xz/src/liblzma/common/block_util.c [] []
/src/xz/src/liblzma/check/sha256.c ['fuzz_encode_stream', 'fuzz_decode_stream', 'fuzz_decode_stream_mt'] ['fuzz_decode_stream', 'fuzz_decode_stream_mt']

Directories in report

Directory
/usr/local/lib/clang/22/include/
/src/xz/src/liblzma/lzma/
/src/xz/src/liblzma/../../src/liblzma/lz/
/src/xz/src/liblzma/lz/
/src/xz/src/liblzma/check/
/src/xz/src/liblzma/simple/
/src/xz/src/liblzma/delta/
/src/xz/src/liblzma/common/
/src/xz/src/liblzma/../../src/liblzma/rangecoder/
/src/xz/tests/ossfuzz/
/src/xz/tests/ossfuzz/./
/src/xz/src/liblzma/../../src/common/