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

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 27.7%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 13 72.2%
All colors 18 100

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
2 2 1 :

['abort']

2 2 fuzz_code call site: 00012 /src/xz/tests/ossfuzz/./fuzz_common.h:51
0 4 1 :

['lzma_free']

0 4 lzma_next_end call site: 00006 /src/xz/src/liblzma/common/common.c:152
0 0 None 0 46 lzma_decode call site: 00000 /src/xz/src/liblzma/lzma/lzma_decoder.c:680
0 0 None 0 28 lzma_decoder_init call site: 00000 /src/xz/src/liblzma/lzma/lzma_decoder.c:1148
0 0 None 0 25 alone_decode call site: 00000 /src/xz/src/liblzma/common/alone_decoder.c:76
0 0 None 0 13 lz_decode call site: 00000 /src/xz/src/liblzma/lz/lz_decoder.c:149
0 0 None 0 12 lzma_lz_decoder_init call site: 00000 /src/xz/src/liblzma/lz/lz_decoder.c:293
0 0 None 0 4 lz_decoder_end call site: 00000 /src/xz/src/liblzma/lz/lz_decoder.c:208
0 0 None 0 4 lzma_lzma_decoder_memusage call site: 00000 /src/xz/src/liblzma/lzma/lzma_decoder.c:1226
0 0 None 0 2 decode_buffer call site: 00000 /src/xz/src/liblzma/lz/lz_decoder.c:115
0 0 None 0 0 lzma_alone_decoder_init call site: 00005 /src/xz/src/liblzma/common/alone_decoder.c:215
0 0 None 0 0 alone_decode call site: 00000 /src/xz/src/liblzma/common/alone_decoder.c:116

Runtime coverage analysis

Covered functions
37
Functions that are reachable but not covered
2
Reachable functions
12
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
/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 18 25.0%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 54 75.0%
All colors 72 100

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
42 42 1 :

['encode_eopm']

42 57 lzma_lzma_encode call site: 00000 /src/xz/src/liblzma/lzma/lzma_encoder.c:418
4 4 2 :

['ctz32', 'bsr32']

4 4 index_tree_append call site: 00027 /src/xz/src/liblzma/common/index.c:239
2 2 1 :

['move_window']

2 5 fill_window call site: 00000 /src/xz/src/liblzma/lz/lz_encoder.c:87
2 2 1 :

['abort']

2 2 fuzz_code call site: 00066 /src/xz/tests/ossfuzz/./fuzz_common.h:51
0 56 5 :

['fold', 'fold_xor', 'my_load128', 'shift_right', 'keep_high_bytes']

0 60 crc32_arch_optimized call site: 00000 /src/xz/src/liblzma/check/crc_x86_clmul.h:204
0 15 1 :

['index_tree_next']

0 35 lzma_index_iter_next call site: 00000 /src/xz/src/liblzma/common/index.c:1204
0 8 1 :

['lzma_vli_encode']

0 37 lzma_block_header_encode call site: 00000 /src/xz/src/liblzma/common/block_header_encoder.c:99
0 8 2 :

['read64le', 'shift_left']

0 8 crc32_arch_optimized call site: 00000 /src/xz/src/liblzma/check/crc_x86_clmul.h:214
0 8 1 :

['lzma_next_end']

0 8 lzma_raw_coder_init call site: 00056 /src/xz/src/liblzma/common/filter_common.c:343
0 8 1 :

['lzma_free']

0 8 lz_encoder_init call site: 00000 /src/xz/src/liblzma/lz/lz_encoder.c:426
0 4 1 :

['lzma_free']

0 4 lzma_next_end call site: 00010 /src/xz/src/liblzma/common/common.c:152
0 4 1 :

['lzma_free']

0 4 lzma_index_init call site: 00023 /src/xz/src/liblzma/common/index.c:405

Runtime coverage analysis

Covered functions
175
Functions that are reachable but not covered
5
Reachable functions
46
Percentage of reachable functions covered
89.13%
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 8
/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 20.8%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 19 79.1%
All colors 24 100

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
2 2 1 :

['abort']

2 2 fuzz_code call site: 00018 /src/xz/tests/ossfuzz/./fuzz_common.h:51
0 25 1 :

['lzma_check_update']

4 59 block_decode call site: 00000 /src/xz/src/liblzma/common/block_decoder.c:128
0 4 1 :

['lzma_free']

0 4 lzma_next_end call site: 00006 /src/xz/src/liblzma/common/common.c:152
0 3 1 :

['lzma_bufcpy']

0 3 copy_or_code call site: 00000 /src/xz/src/liblzma/simple/simple_coder.c:27
0 0 None 4 9 block_decode call site: 00000 /src/xz/src/liblzma/common/block_decoder.c:172
0 0 None 2 447 stream_decode call site: 00000 /src/xz/src/liblzma/common/stream_decoder.c:150
0 0 None 2 447 stream_decode call site: 00000 /src/xz/src/liblzma/common/stream_decoder.c:330
0 0 None 0 84 lzma_block_header_decode call site: 00000 /src/xz/src/liblzma/common/block_header_decoder.c:38
0 0 None 0 59 lzma_block_decoder_init call site: 00000 /src/xz/src/liblzma/common/block_decoder.c:223
0 0 None 0 46 lzma_decode call site: 00000 /src/xz/src/liblzma/lzma/lzma_decoder.c:680
0 0 None 0 23 lzma_lz_decoder_init call site: 00000 /src/xz/src/liblzma/lz/lz_decoder.c:254
0 0 None 0 20 lzma_raw_coder_init call site: 00000 /src/xz/src/liblzma/common/filter_common.c:308

Runtime coverage analysis

Covered functions
141
Functions that are reachable but not covered
2
Reachable functions
16
Percentage of reachable functions covered
87.5%
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

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
lzma2_encode /src/xz/src/liblzma/lzma/lzma2_encoder.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t'] 6 0 362 42 12 63 0 395 395
stream_decode /src/xz/src/liblzma/common/stream_decoder.c 9 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t', 'N/A', 'N/A', 'size_t', 'int'] 6 0 715 101 33 51 0 307 231
lzma_decode /src/xz/src/liblzma/lzma/lzma_decoder.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'size_t'] 2 0 5182 617 127 7 0 149 149
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 0 388 50 15 43 0 226 87
lzma_lzma2_encoder_init /src/xz/src/liblzma/lzma/lzma2_encoder.c 3 ['N/A', 'N/A', 'N/A'] 7 0 24 3 2 24 0 131 66
lzma_index_buffer_encode /src/xz/src/liblzma/common/index_encoder.c 4 ['N/A', 'N/A', 'N/A', 'size_t'] 6 0 108 18 8 16 0 83 56
lzma_mf_bt4_find /src/xz/src/liblzma/lz/lz_encoder_mf.c 2 ['N/A', 'N/A'] 2 0 485 44 16 8 0 58 52
lzma_lzma_decoder_init /src/xz/src/liblzma/lzma/lzma_decoder.c 3 ['N/A', 'N/A', 'N/A'] 4 0 24 3 2 12 0 67 44

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

Functions statically reachable by fuzzers
53.0%
197 / 369
Cyclomatic complexity statically reachable by fuzzers
63.0%
1333 / 2103

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

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/../../src/liblzma/rangecoder/range_encoder.h [] []
/src/xz/src/liblzma/common/alone_decoder.c ['fuzz_decode_alone'] ['fuzz_decode_alone']
/src/xz/tests/ossfuzz/fuzz_decode_alone.c ['fuzz_decode_alone'] ['fuzz_decode_alone']
/src/xz/src/liblzma/../../src/liblzma/lz/lz_encoder.h [] []
/src/xz/src/liblzma/simple/powerpc.c [] []
/src/xz/src/liblzma/delta/delta_decoder.c [] []
/src/xz/src/liblzma/common/index_encoder.c [] []
/src/xz/src/liblzma/common/vli_decoder.c [] []
/src/xz/src/liblzma/delta/delta_common.c [] []
/src/xz/src/liblzma/lzma/lzma_encoder.c [] []
/src/xz/src/liblzma/simple/armthumb.c [] []
/src/xz/src/liblzma/common/stream_flags_common.c [] []
/src/xz/src/liblzma/simple/x86.c [] []
/src/xz/src/liblzma/common/stream_flags_common.h [] []
/src/xz/src/liblzma/common/index.h [] []
/src/xz/tests/ossfuzz/fuzz_encode_stream.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/simple/riscv.c [] []
/src/xz/src/liblzma/../../src/liblzma/lz/lz_decoder.h [] []
/src/xz/src/liblzma/delta/delta_encoder.c [] []
/src/xz/src/liblzma/../../src/common/tuklib_integer.h ['fuzz_encode_stream'] []
/src/xz/src/liblzma/common/filter_decoder.c [] []
/src/xz/src/liblzma/lzma/fastpos.h [] []
/usr/local/lib/clang/18/include/cpuid.h [] []
/src/xz/src/liblzma/simple/simple_encoder.c [] []
/src/xz/src/liblzma/simple/ia64.c [] []
/src/xz/src/liblzma/common/filter_common.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/block_header_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/filter_flags_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/block_decoder.c [] []
/src/xz/src/liblzma/check/crc_x86_clmul.h [] []
/src/xz/src/liblzma/common/stream_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/simple/sparc.c [] []
/src/xz/src/liblzma/common/vli_encoder.c [] []
/src/xz/src/liblzma/common/block_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lz/lz_encoder.c [] []
/src/xz/src/liblzma/lzma/lzma_encoder_optimum_normal.c [] []
/src/xz/tests/ossfuzz/fuzz_decode_stream.c ['fuzz_decode_stream'] ['fuzz_decode_stream']
/src/xz/src/liblzma/lz/lz_encoder.h [] []
/src/xz/src/liblzma/../../src/liblzma/rangecoder/range_decoder.h [] []
/src/xz/src/liblzma/lzma/lzma_encoder_optimum_fast.c [] []
/src/xz/src/liblzma/common/stream_flags_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/filter_flags_decoder.c [] []
/src/xz/src/liblzma/simple/arm.c [] []
/src/xz/src/liblzma/common/index.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/../../src/liblzma/rangecoder/price.h [] []
/src/xz/src/liblzma/common/common.c ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream'] ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream']
/src/xz/src/liblzma/lzma/lzma2_decoder.c [] []
/src/xz/src/liblzma/simple/arm64.c [] []
/src/xz/src/liblzma/common/vli_size.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lzma/lzma_common.h [] []
/src/xz/src/liblzma/common/block_util.c [] []
/src/xz/src/liblzma/common/stream_flags_decoder.c [] []
/src/xz/tests/ossfuzz/./fuzz_common.h ['fuzz_decode_alone', 'fuzz_encode_stream', 'fuzz_decode_stream'] []
/src/xz/src/liblzma/check/crc32_fast.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lzma/lzma_decoder.c [] []
/src/xz/src/liblzma/lzma/lzma_encoder_presets.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/common/filter_encoder.c ['fuzz_encode_stream'] ['fuzz_encode_stream']
/src/xz/src/liblzma/lzma/lzma2_encoder.c [] []
/src/xz/src/liblzma/simple/simple_coder.c [] []
/src/xz/src/liblzma/simple/simple_decoder.c [] []
/src/xz/src/liblzma/common/stream_decoder.c ['fuzz_decode_stream'] ['fuzz_decode_stream']
/src/xz/src/liblzma/common/index_hash.c ['fuzz_decode_stream'] ['fuzz_decode_stream']
/src/xz/src/liblzma/lz/lz_encoder_mf.c [] []
/src/xz/src/liblzma/lz/lz_decoder.c [] []
/src/xz/src/liblzma/check/crc64_fast.c [] []
/src/xz/src/liblzma/check/check.c ['fuzz_encode_stream', 'fuzz_decode_stream'] ['fuzz_encode_stream', 'fuzz_decode_stream']
/src/xz/src/liblzma/common/block_header_decoder.c [] []
/src/xz/src/liblzma/check/sha256.c ['fuzz_encode_stream', 'fuzz_decode_stream'] ['fuzz_decode_stream']

Directories in report

Directory
/src/xz/src/liblzma/common/
/src/xz/src/liblzma/../../src/common/
/usr/local/lib/clang/18/include/
/src/xz/tests/ossfuzz/
/src/xz/src/liblzma/../../src/liblzma/rangecoder/
/src/xz/src/liblzma/simple/
/src/xz/src/liblzma/lzma/
/src/xz/src/liblzma/check/
/src/xz/src/liblzma/../../src/liblzma/lz/
/src/xz/src/liblzma/delta/
/src/xz/tests/ossfuzz/./
/src/xz/src/liblzma/lz/