Fuzz introspector
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Project coverage
Per-fuzzer coverage

Table of contents

Project overview: libbpf
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: bpf-object-fuzzer
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/bpf-object-fuzzer.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: 2026-07-16

Project overview: libbpf

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
27.0%
312 / 1143
Cyclomatic complexity statically reachable by fuzzers
28.0%
2178 / 7662
Runtime code coverage of functions
25.0%
286 / 1143

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
bpf-object-fuzzer fuzz/bpf-object-fuzzer.c 359 873 13 39 5648 2273 bpf-object-fuzzer.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: bpf-object-fuzzer

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 0 512 35.5%
gold [1:9] 78 5.41%
yellow [10:29] 52 3.60%
greenyellow [30:49] 31 2.15%
lawngreen 50+ 768 53.2%
All colors 1441 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
142 1032 create_placeholder_fd call site: 01032 parse_btf_map_def
61 119 libbpf_errstr call site: 00119 elf_begin
34 1324 bpf_object__collect_map_relos call site: 01324 bpf_object__find_map_by_name
30 1281 bpf_object_open call site: 01281 bpf_object__collect_st_ops_relos
12 247 load_shdr_wrlock call site: 00247 pread_retry
9 340 __libelf_decompress_elf call site: 00340 elf32_getchdr
8 199 bpf_object__elf_init call site: 00199 pread_retry
7 1021 create_placeholder_fd call site: 01021 dup_good_fd
6 269 load_shdr_wrlock call site: 00269 __bswap_64
6 791 btf__add_var call site: 00791 btf__find_str
6 867 btf__resolve_size call site: 00867 determine_ptr_size
5 193 elf64_getehdr call site: 00193 elf_errmsg

Runtime coverage analysis

Covered functions
287
Functions that are reachable but not covered
97
Reachable functions
359
Percentage of reachable functions covered
72.98%
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/bpf-object-fuzzer.c 2
src/libbpf.c 114
src/./libbpf_internal.h 19
src/../include/linux/err.h 4
elfutils/libelf/elf_version.c 1
elfutils/libelf/elf_error.c 2
src/libbpf_probes.c 3
elfutils/libelf/elf_memory.c 1
elfutils/libelf/elf_begin.c 12
elfutils/libelf/./common.h 2
/usr/include/x86_64-linux-gnu/bits/byteswap.h 3
elfutils/libelf/../lib/system.h 1
src/libbpf_utils.c 1
elfutils/libelf/elf_kind.c 1
elfutils/libelf/gelf_getclass.c 1
elfutils/libelf/./elf32_getehdr.c 2
elfutils/libelf/elf_getshdrstrndx.c 1
elfutils/libelf/elf_getscn.c 1
elfutils/libelf/elf_rawdata.c 1
elfutils/libelf/elf_getdata.c 7
elfutils/libelf/elf32_getshdr.c 5
elfutils/libelf/elf_getshdrnum.c 2
elfutils/libelf/./elf32_getshdr.c 5
elfutils/libelf/gelf_getehdr.c 1
elfutils/libelf/elf_end.c 1
elfutils/libelf/elf_nextscn.c 1
elfutils/libelf/elf_ndxscn.c 1
elfutils/libelf/elf_strptr.c 3
elfutils/libelf/elf_compress.c 3
elfutils/libelf/gelf_getchdr.c 1
elfutils/libelf/elf32_getchdr.c 1
elfutils/libelf/./elf32_getchdr.c 1
src/btf.c 58
src/./btf.h 29
src/strset.c 10
src/hashmap.c 10
src/./hashmap.h 2
src/usdt.c 1
src/gen_loader.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
bpf_object__load_skeleton /src/libbpf/src/libbpf.c 1 ['N/A'] 19 0 123 17 6 541 0 3511 2124
attach_usdt /src/libbpf/src/libbpf.c 3 ['N/A', 'size_t', 'N/A'] 14 0 84 11 4 233 0 1687 819
btf__dedup /src/libbpf/src/btf.c 2 ['N/A', 'N/A'] 11 0 209 48 14 125 0 632 368
attach_tracing_multi /src/libbpf/src/libbpf.c 3 ['N/A', 'size_t', 'N/A'] 18 0 163 26 9 236 0 1582 97
btf__distill_base /src/libbpf/src/btf.c 3 ['N/A', 'N/A', 'N/A'] 11 0 297 45 18 81 0 371 97
attach_kprobe_multi /src/libbpf/src/libbpf.c 3 ['N/A', 'size_t', 'N/A'] 7 0 125 16 6 55 0 340 92
elf_compress /src/libbpf/elfutils/libelf/elf_compress.c 3 ['N/A', 'int', 'int'] 10 0 547 65 27 45 0 332 92
bpf_program__clone /src/libbpf/src/libbpf.c 2 ['N/A', 'N/A'] 6 0 1231 239 83 25 0 235 83
libbpf_prepare_prog_load /src/libbpf/src/libbpf.c 3 ['N/A', 'N/A', 'size_t'] 11 0 242 38 15 99 0 465 75
perf_buffer__new_raw /src/libbpf/src/libbpf.c 6 ['int', 'size_t', 'N/A', 'N/A', 'N/A', 'N/A'] 6 0 158 29 11 40 0 155 64

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

Functions statically reachable by fuzzers
68.0%
782 / 1143
Cyclomatic complexity statically reachable by fuzzers
79.0%
6015 / 7662

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/bpf-object-fuzzer.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=['create_placeholder_fd', 'libbpf_errstr', 'bpf_object__collect_map_relos', 'bpf_object_open', 'load_shdr_wrlock', '__libelf_decompress_elf', 'bpf_object__elf_init', 'btf__add_var']

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
load_shdr_wrlock 133 67 50.37% ['bpf-object-fuzzer']
__elf_getdata_rdlock 50 22 44.0% ['bpf-object-fuzzer']
elf_getscn 63 30 47.61% ['bpf-object-fuzzer']
elf_getshdrstrndx 142 61 42.95% ['bpf-object-fuzzer']
__gelf_getehdr_rdlock 39 12 30.76% ['bpf-object-fuzzer']
bpf_object__init_user_btf_map 85 26 30.58% ['bpf-object-fuzzer']
bpf_object__collect_map_relos 119 42 35.29% ['bpf-object-fuzzer']
libbpf_errstr 63 12 19.04% ['bpf-object-fuzzer']

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/libbpf/src/./libbpf_internal.h ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/elf_strptr.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/../lib/system.h ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/elf_begin.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/./note_xlate.h [] []
/src/libbpf/elfutils/libelf/./gnuhash_xlate.h [] []
/src/libbpf/src/btf_iter.c [] []
/src/libbpf/elfutils/libelf/gelf_getverdef.c [] []
/src/libbpf/elfutils/libelf/./elf32_getchdr.c ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/elf32_getshdr.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/features.c [] []
/src/libbpf/elfutils/libelf/elf32_xlatetof.c [] []
/src/libbpf/elfutils/libelf/elf_nextscn.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getphdr.c [] []
/src/libbpf/src/usdt.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_getphdrnum.c [] []
/src/libbpf/elfutils/libelf/./common.h ['bpf-object-fuzzer'] []
/src/libbpf/src/strset.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_getshdrstrndx.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_compress.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_xlatetof.c [] []
/src/libbpf/elfutils/libelf/elf_version.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_rawdata.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/relo_core.c [] []
/src/libbpf/elfutils/libelf/gelf_getsym.c [] []
/src/libbpf/elfutils/libelf/./chdr_xlate.h [] []
/src/libbpf/src/zip.c [] []
/src/libbpf/elfutils/libelf/gelf_fsize.c [] []
/src/libbpf/elfutils/libelf/elf_memory.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/fuzz/bpf-object-fuzzer.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/./elf32_getphdr.c [] []
/src/libbpf/elfutils/libelf/gelf_getnote.c [] []
/src/libbpf/src/../include/linux/err.h ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/./elf32_getshdr.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getshdr.c [] []
/usr/include/x86_64-linux-gnu/bits/byteswap.h ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/./elf32_getehdr.c ['bpf-object-fuzzer'] []
/src/libbpf/elfutils/libelf/gelf_getversym.c [] []
/src/libbpf/src/libbpf_probes.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_end.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/./gelf_xlate.h [] []
/src/libbpf/elfutils/libelf/gelf_xlate.c [] []
/src/libbpf/src/gen_loader.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/elf.c [] []
/src/libbpf/elfutils/libelf/elf_kind.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getverdaux.c [] []
/src/libbpf/elfutils/libelf/elf_ndxscn.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf32_getchdr.c ['bpf-object-fuzzer'] []
/src/libbpf/src/./hashmap.h ['bpf-object-fuzzer'] []
/src/libbpf/src/btf.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getchdr.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getclass.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf_getshdrnum.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/./btf.h ['bpf-object-fuzzer'] []
/src/libbpf/src/btf_relocate.c [] []
/src/libbpf/src/../include/linux/ring_buffer.h [] []
/src/libbpf/elfutils/libelf/elf_getscn.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/elf32_getphdr.c [] []
/src/libbpf/elfutils/libelf/./elf32_xlatetof.c [] []
/src/libbpf/elfutils/libelf/elf_getdata.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/./version_xlate.h [] []
/src/libbpf/elfutils/libelf/elf_error.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/hashmap.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/bpf.c [] []
/src/libbpf/src/libbpf_utils.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/elfutils/libelf/gelf_getehdr.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']
/src/libbpf/src/libbpf.c ['bpf-object-fuzzer'] ['bpf-object-fuzzer']

Directories in report

Directory
/usr/include/x86_64-linux-gnu/bits/
/src/libbpf/src/
/src/libbpf/src/../include/linux/
/src/libbpf/elfutils/libelf/./
/src/libbpf/fuzz/
/src/libbpf/elfutils/libelf/
/src/libbpf/elfutils/libelf/../lib/
/src/libbpf/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
bpf-object-fuzzer fuzzerLogFile-0-yVqJsj6SXA.data fuzzerLogFile-0-yVqJsj6SXA.data.yaml bpf-object-fuzzer.covreport