Fuzz introspector
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Project coverage
Per-fuzzer coverage

Table of contents

Project overview: libunwind
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: fuzz_libunwind
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Fuzz engine guidance
fuzz_libunwind.c
Dictionary
Fuzzer function priority
Runtime coverage analysis
Complex functions with low coverage
Files and Directories in report
Files in report
Directories in report
Metadata section
Report generation date: 2026-10-17

Project overview: libunwind

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
68.0%
119 / 176
Cyclomatic complexity statically reachable by fuzzers
73.0%
873 / 1198
Runtime code coverage of functions
66.0%
117 / 176

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_libunwind fuzz_libunwind.c 141 70 16 34 2417 919 fuzz_libunwind.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 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_libunwind

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 0 195 47.4%
gold [1:9] 26 6.32%
yellow [10:29] 75 18.2%
greenyellow [30:49] 4 0.97%
lawngreen 50+ 111 27.0%
All colors 411 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
33 309 _ULx86_64_access_reg call site: 00309 eval_location_expr
25 356 _ULx86_64_step call site: 00356 _unw_step_fallback
14 267 run_cfi_program call site: 00267 dwarf_read_sleb128
12 343 apply_reg_state call site: 00343 _ULx86_64_stash_frame
11 16 unw_init_page_size call site: 00016 __errno_location
9 227 read_regnum call site: 00227 _ULx86_64_dwarf_read_encoded_pointer
9 238 run_cfi_program call site: 00238 push_rstate_stack
6 86 get_rs_cache call site: 00086 syscall
6 163 _UIx86_64__mempool_alloc call site: 00163 pthread_mutex_unlock
5 32 expand call site: 00032 _UIx86_64__sos_alloc
5 176 _ULx86_64_dwarf_find_proc_info call site: 00176 dwarf_find_eh_frame_section
5 194 _Uelf64_find_section call site: 00194 linear_search

Runtime coverage analysis

Covered functions
121
Functions that are reachable but not covered
54
Reachable functions
141
Percentage of reachable functions covered
61.7%
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
fuzz_libunwind.c 10
libunwindx86_64/Ginit_local.c 2
libunwindx86_64/Gglobal.c 1
libunwindmi/init.c 2
libunwinddwarf/global.c 1
libunwindmi/mempool.c 7
libunwindx86_64/Ginit.c 1
libunwindmi/flush_cache.c 1
libunwind../include/tdep-x86_64/libunwind_i.h 6
libunwindx86_64/init.h 1
libunwindx86_64/Gos-linux.c 8
libunwindx86_64/Gstep.c 5
libunwinddwarf/Gparser.c 26
libunwindmi/Gfind_dynamic_proc_info.c 3
libunwindmi/dyn-info-list.c 1
libunwindmi/Gdyn-extract.c 1
libunwinddwarf/Gfind_proc_info-lsb.c 7
libunwindmi/Gget_accessors.c 1
libunwinddwarf/Gfind_proc_info_i.h 2
libunwinddwarf/Gfde.c 3
libunwind../include/dwarf_i.h 10
libunwinddwarf/Gpe.c 1
libunwindmi/Giterate_phdr_for_ip.c 1
libunwindos-linux.c 1
libunwind./elfxx.h 2
libunwind./elfxx.c 3
libunwindmi/Gput_dynamic_unwind_info.c 1
libunwindmi/Gget_reg.c 1
libunwindx86_64/Gregs.c 1
libunwinddwarf/Gexpr.c 4
libunwindx86_64/Gstash_frame.c 1
libunwindmi/Gget_proc_name.c 3
libunwind../include/remote.h 1
libunwindx86_64/Gget_save_loc.c 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
get_static_proc_name /src/libunwind/src/x86_64/Ginit.c 6 ['N/A', 'size_t', 'N/A', 'size_t', 'N/A', 'N/A'] 9 0 31 3 2 72 0 337 228
access_mem /src/libunwind/src/x86_64/Ginit.c 5 ['N/A', 'size_t', 'N/A', 'int', 'N/A'] 5 0 72 12 5 12 0 49 41

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

Functions statically reachable by fuzzers
88.0%
154 / 176
Cyclomatic complexity statically reachable by fuzzers
93.0%
1120 / 1198

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.

fuzz_libunwind.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=['_ULx86_64_access_reg', '_ULx86_64_step', 'run_cfi_program', 'apply_reg_state', 'unw_init_page_size', 'read_regnum', 'get_rs_cache', '_UIx86_64__mempool_alloc', 'expand']

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
dwarf_read_encoded_pointer_inlined 107 40 37.38%
parse_cie 133 68 51.12% ['fuzz_libunwind']
_ULx86_64_dwarf_flush_rs_cache 42 20 47.61% ['fuzz_libunwind']
run_cfi_program 234 75 32.05% ['fuzz_libunwind']
_ULx86_64_get_proc_name_by_ip 33 11 33.33% ['fuzz_libunwind']
_Ux86_64_get_elf_image 125 42 33.6% ['fuzz_libunwind']

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/libunwind/src/../include/tdep-x86_64/libunwind_i.h ['fuzz_libunwind'] []
/src/libunwind/src/dwarf/Gfde.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/dwarf/Gfind_proc_info-lsb.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/dyn-info-list.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/./os-linux.h [] []
/src/libunwind/src/x86_64/Gresume.c [] []
/src/libunwind/src/mi/Gaddress_validator.c [] []
/src/libunwind/src/mi/Gget_proc_name.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/dwarf/Gpe.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/Gregs.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/Giterate_phdr_for_ip.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/init.h ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/Ginit_local.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/./elfxx_i.h [] []
/src/libunwind/src/x86_64/Gglobal.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/../include/remote.h ['fuzz_libunwind'] []
/src/libunwind/src/dwarf/global.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/is_fpreg.c [] []
/src/libunwind/src/dwarf/Gparser.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/Gstash_frame.c ['fuzz_libunwind'] []
/src/libunwind/src/mi/mempool.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/os-linux.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/./elfxx.c ['fuzz_libunwind'] []
/src/libunwind/src/mi/Gfind_dynamic_proc_info.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/dwarf/Gfind_proc_info_i.h ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/Gget_accessors.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/../include/dwarf_i.h ['fuzz_libunwind'] []
/src/libunwind/src/mi/Gput_dynamic_unwind_info.c ['fuzz_libunwind'] []
/src/libunwind/src/./elfxx.h ['fuzz_libunwind'] []
/src/libunwind/src/mi/Gget_reg.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/Ginit.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/init.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/dwarf/Gexpr.c ['fuzz_libunwind'] []
/src/libunwind/src/x86_64/Gstep.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/fuzz_libunwind.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/flush_cache.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/../include/libunwind_i.h [] []
/src/libunwind/src/x86_64/Gos-linux.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/x86_64/Gget_save_loc.c ['fuzz_libunwind'] ['fuzz_libunwind']
/src/libunwind/src/mi/Gdyn-extract.c ['fuzz_libunwind'] []

Directories in report

Directory
/src/libunwind/src/../include/tdep-x86_64/
/src/libunwind/src/./
/src/libunwind/src/x86_64/
/src/
/src/libunwind/src/../include/
/src/libunwind/src/dwarf/
/src/libunwind/src/mi/
/src/libunwind/src/

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
fuzz_libunwind fuzzerLogFile-0-nhy4OVsKOJ.data fuzzerLogFile-0-nhy4OVsKOJ.data.yaml fuzz_libunwind.covreport