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

Table of contents

Project overview: libnfs
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: libnfs_reply_fuzzer
Call tree
Runtime coverage analysis
Files reached
Fuzzer: libnfs_zdr_roundtrip_fuzzer
Call tree
Runtime coverage analysis
Files reached
Fuzzer: libnfs_url_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
fuzzing/libnfs_reply_fuzzer.c
Dictionary
Fuzzer function priority
fuzzing/libnfs_zdr_roundtrip_fuzzer.c
Dictionary
Fuzzer function priority
fuzzing/libnfs_url_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: 2026-11-12

Project overview: libnfs

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
5.0%
64 / 1394
Cyclomatic complexity statically reachable by fuzzers
4.0%
292 / 7103
Runtime code coverage of functions
32.0%
449 / 1394

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
libnfs_reply_fuzzer fuzzing/libnfs_reply_fuzzer.c 4 881 1 2 21 13 libnfs_reply_fuzzer.c
libnfs_zdr_roundtrip_fuzzer fuzzing/libnfs_zdr_roundtrip_fuzzer.c 5 880 1 2 36 20 libnfs_zdr_roundtrip_fuzzer.c
libnfs_url_fuzzer fuzzing/libnfs_url_fuzzer.c 82 1330 7 8 575 336 libnfs_url_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: libnfs_reply_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 0 0.0%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 4 100.%
All colors 4 100

Runtime coverage analysis

Covered functions
398
Functions that are reachable but not covered
1
Reachable functions
4
Percentage of reachable functions covered
75.0%
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
fuzzing/libnfs_reply_fuzzer.c 1
lib/libnfs-zdr.c 2

Fuzzer: libnfs_zdr_roundtrip_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 0 0.0%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 10 100.%
All colors 10 100

Runtime coverage analysis

Covered functions
398
Functions that are reachable but not covered
1
Reachable functions
5
Percentage of reachable functions covered
80.0%
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
fuzzing/libnfs_zdr_roundtrip_fuzzer.c 1
lib/libnfs-zdr.c 3

Fuzzer: libnfs_url_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 38 17.9%
gold [1:9] 2 0.94%
yellow [10:29] 4 1.88%
greenyellow [30:49] 1 0.47%
lawngreen 50+ 167 78.7%
All colors 212 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
6 47 rpc_purge_all_pdus call site: 00047 rpc_free_pdu
5 61 rpc_destroy_context call site: 00061 nfs_free_nfsdir
4 198 nfs_parse_url call site: 00198 rpc_set_error
3 9 rpc_init_context call site: 00009 libnfs_authunix_create
3 102 nfs_parse_url call site: 00102 nfs_set_error
2 23 libnfs_authunix_create call site: 00023 __bswap_32
2 54 rpc_purge_all_pdus call site: 00054 rpc_free_pdu
2 74 nfs_parse_url call site: 00074 nfs_set_error
2 85 nfs_parse_url call site: 00085 nfs_set_error
2 96 nfs_parse_url call site: 00096 nfs_set_error
2 99 nfs_parse_url call site: 00099 nfs_set_error
1 40 nfs_init_context call site: 00040 nfs_destroy_context

Runtime coverage analysis

Covered functions
57
Functions that are reachable but not covered
29
Reachable functions
82
Percentage of reachable functions covered
64.63%
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
fuzzing/libnfs_url_fuzzer.c 1
lib/libnfs.c 29
lib/init.c 19
lib/pdu.c 2
lib/libnfs-zdr.c 5
/usr/include/x86_64-linux-gnu/bits/byteswap.h 1
lib/socket.c 3
nfs4/nfs4.c 3

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
nfs_creat_async /src/libnfs/lib/libnfs.c 5 ['N/A', 'N/A', 'int', 'N/A', 'N/A'] 16 0 52 11 2 459 0 2529 2460
nfs_service /src/libnfs/lib/libnfs.c 2 ['N/A', 'int'] 15 0 57 13 6 401 0 2185 520
nfs_mount_async /src/libnfs/lib/libnfs.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 19 0 12 3 2 185 0 989 336
nfs_opendir_async /src/libnfs/lib/libnfs.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 16 0 39 9 10 444 0 2510 205
nfs_write_async /src/libnfs/lib/libnfs.c 6 ['N/A', 'N/A', 'N/A', 'size_t', 'N/A', 'N/A'] 16 0 61 13 3 394 0 2193 184
r_cb /src/libnfs/lib/libnfs.c 4 ['int', 'N/A', 'N/A', 'N/A'] 14 0 122 22 9 367 4 2021 104
rpc_nfs2_mkdir_task /src/libnfs/nfs/nfs.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 10 0 44 10 5 76 0 410 99
nfs_statvfs64_async /src/libnfs/lib/libnfs.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 14 0 39 9 10 398 0 2178 84
nfs_close_async /src/libnfs/lib/libnfs.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 15 0 54 13 2 375 0 2021 73
nfs_rename_async /src/libnfs/lib/libnfs.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 15 0 52 11 2 431 0 2383 63

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

Functions statically reachable by fuzzers
52.0%
731 / 1394
Cyclomatic complexity statically reachable by fuzzers
61.0%
4359 / 7103

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.

fuzzing/libnfs_reply_fuzzer.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/libnfs_zdr_roundtrip_fuzzer.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/libnfs_url_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=['rpc_purge_all_pdus', 'rpc_destroy_context', 'nfs_parse_url', 'rpc_init_context', 'libnfs_authunix_create']

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
zdr_FSINFO3resok 97 46 47.42% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer']
zdr_PATHCONF3resok 71 34 47.88% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer']
zdr_fattr2 121 55 45.45% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer']
zdr_STATFS2resok 57 28 49.12% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer']
zdr_rpc_gss_init_res 53 28 52.83% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer']
zdr_GETQUOTA1res_ok 98 44 44.89% ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_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/libnfs/lib/libnfs-zdr.c ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer', 'libnfs_url_fuzzer'] ['libnfs_reply_fuzzer', 'libnfs_zdr_roundtrip_fuzzer', 'libnfs_url_fuzzer']
/src/libnfs/nfs/libnfs-raw-nfs.c [] []
/src/libnfs/portmap/portmap.c [] []
/src/libnfs/nfs4/libnfs-raw-nfs4.c [] []
/src/libnfs/mount/mount.c [] []
/src/libnfs/lib/init.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']
/src/libnfs/portmap/libnfs-raw-portmap.c [] []
/src/libnfs/lib/libnfs.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']
/usr/include/x86_64-linux-gnu/bits/byteswap.h ['libnfs_url_fuzzer'] []
/src/libnfs/fuzzing/libnfs_url_fuzzer.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']
/src/libnfs/nlm/libnfs-raw-nlm.c [] []
/src/libnfs/rquota/libnfs-raw-rquota.c [] []
/src/libnfs/fuzzing/libnfs_reply_fuzzer.c ['libnfs_reply_fuzzer'] ['libnfs_reply_fuzzer']
/src/libnfs/lib/nfs_v4.c [] []
/src/libnfs/nfs/nfs.c [] []
/src/libnfs/lib/socket.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']
/src/libnfs/fuzzing/libnfs_zdr_roundtrip_fuzzer.c ['libnfs_zdr_roundtrip_fuzzer'] ['libnfs_zdr_roundtrip_fuzzer']
/src/libnfs/lib/nfs_v3.c [] []
/src/libnfs/nfs/nfsacl.c [] []
/src/libnfs/nfs4/nfs4.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']
/src/libnfs/mount/libnfs-raw-mount.c [] []
/src/libnfs/lib/pdu.c ['libnfs_url_fuzzer'] ['libnfs_url_fuzzer']

Directories in report

Directory
/src/libnfs/portmap/
/src/libnfs/mount/
/src/libnfs/fuzzing/
/src/libnfs/nlm/
/src/libnfs/rquota/
/src/libnfs/nfs/
/usr/include/x86_64-linux-gnu/bits/
/src/libnfs/lib/
/src/libnfs/nfs4/

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
libnfs_reply_fuzzer fuzzerLogFile-0-eoqZOCotoa.data fuzzerLogFile-0-eoqZOCotoa.data.yaml libnfs_reply_fuzzer.covreport
libnfs_zdr_roundtrip_fuzzer fuzzerLogFile-0-s1TMiVaqpi.data fuzzerLogFile-0-s1TMiVaqpi.data.yaml libnfs_zdr_roundtrip_fuzzer.covreport
libnfs_url_fuzzer fuzzerLogFile-0-CZZIU80HrM.data fuzzerLogFile-0-CZZIU80HrM.data.yaml libnfs_url_fuzzer.covreport