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

Table of contents

Project overview: postfix
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: fuzz_tok822
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Fuzzer: fuzz_mime
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_tok822.c
Dictionary
Fuzzer function priority
fuzz_mime.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: 2025-12-11

Project overview: postfix

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
16.0%
95 / 585
Cyclomatic complexity statically reachable by fuzzers
23.0%
906 / 3944
Runtime code coverage of functions
9.0%
54 / 585

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_tok822 fuzz_tok822.c 66 77 18 16 1374 537 fuzz_tok822.c
fuzz_mime fuzz_mime.c 99 547 22 25 1682 697 fuzz_mime.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_tok822

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 86 35.5%
gold [1:9] 6 2.47%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 150 61.9%
All colors 242 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
30 61 vbuf_print call site: 00061 msg_panic
15 104 msg_vstream_print call site: 00104 vstream_fflush_delayed
9 31 printable_except call site: 00031 mystrdup
4 9 vstring_alloc call site: 00009 msg_panic
4 44 vbuf_print call site: 00044 msg_warn
3 1 LLVMFuzzerTestOneInput call site: 00001 msg_panic
3 92 msg_output call site: 00092 myrealloc
2 41 vbuf_print call site: 00041 msg_panic
2 54 vbuf_print call site: 00054 msg_panic
2 99 msg_vstream_init call site: 00099 msg_panic
2 120 vstream_fflush call site: 00120 sleep
1 19 vbuf_print call site: 00019 vbuf_put

Runtime coverage analysis

Covered functions
47
Functions that are reachable but not covered
23
Reachable functions
66
Percentage of reachable functions covered
65.15%
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_tok822.c 1
postfix/postfixutil/vstring.c 7
postfix/postfixutil/msg.c 8
postfix/postfixutil/msg_output.c 2
postfix/postfixutil/msg_vstream.c 2
postfix/postfixutil/mymalloc.c 4
postfix/postfixutil/vbuf_print.c 1
postfix/postfixutil/vbuf.c 1
postfix/postfixutil/printable.c 1
postfix/postfixutil/./parse_utf8_char.h 1
postfix/postfixutil/mystrerror.c 1
postfix/postfixutil/vstream.c 4
postfix/postfixglobal/tok822_parse.c 10
postfix/postfixglobal/tok822_node.c 2
postfix/postfixglobal/tok822_tree.c 6
postfix/postfixglobal/quote_822_local.c 3

Fuzzer: fuzz_mime

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 0 256 88.5%
gold [1:9] 4 1.38%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 29 10.0%
All colors 289 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
82 170 myfree call site: 00170 mime_state_content_type
79 15 vstring_alloc call site: 00015 msg_panic
34 135 vstring_strncat call site: 00135 header_opts_find
24 257 mime_state_update call site: 00257 mime_state_pop
20 95 vstring_alloc call site: 00095 vstream_fprintf
5 3 msg_output call site: 00003 msg_panic
5 9 msg_vstream_init call site: 00009 msg_panic
3 116 msg_output call site: 00116 myrealloc
2 132 LLVMFuzzerTestOneInput call site: 00132 mime_state_update
1 121 myrealloc call site: 00121 msg_fatal
1 285 vstring_free call site: 00285 mime_state_pop

Runtime coverage analysis

Covered functions
20
Functions that are reachable but not covered
81
Reachable functions
99
Percentage of reachable functions covered
18.18%
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_mime.c 6
postfix/postfixutil/msg_vstream.c 2
postfix/postfixutil/msg_output.c 2
postfix/postfixutil/vstring.c 8
postfix/postfixutil/msg.c 8
postfix/postfixutil/vstream.c 4
postfix/postfixutil/vbuf_print.c 1
postfix/postfixutil/mymalloc.c 5
postfix/postfixutil/vbuf.c 1
postfix/postfixutil/printable.c 1
postfix/postfixutil/./parse_utf8_char.h 1
postfix/postfixutil/mystrerror.c 1
postfix/postfixglobal/mime_state.c 9
postfix/postfixglobal/header_opts.c 3
postfix/postfixutil/htable.c 6
postfix/postfixutil/hash_fnv.c 2
postfix/postfixutil/ldseed.c 1
postfix/postfixutil/non_blocking.c 1
postfix/postfixutil/argv_split.c 1
postfix/postfixutil/argv.c 5
postfix/postfixutil/mystrtok.c 2
postfix/postfixutil/lowercase.c 1
postfix/postfixutil/trimblanks.c 1
postfix/postfixglobal/header_token.c 1
postfix/postfixglobal/is_header.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
dict_regexp_open /src/postfix/postfix/src/util/dict_regexp.c 3 ['N/A', 'int', 'int'] 18 0 305 61 22 109 0 706 402
dict_tcp_lookup /src/postfix/postfix/src/util/dict_tcp.c 2 ['N/A', 'N/A'] 14 0 351 65 23 109 0 701 301
dict_sockmap_lookup /src/postfix/postfix/src/util/dict_sockmap.c 2 ['N/A', 'N/A'] 15 0 271 52 21 89 0 523 173
get_mail_conf_time_table /src/postfix/postfix/src/global/mail_conf_time.c 1 ['N/A'] 16 0 43 9 4 89 2 522 156
mynetworks_core /src/postfix/postfix/src/global/mynetworks.c 1 ['N/A'] 15 0 385 79 20 117 2 597 155
mkmap_btree_open /src/postfix/postfix/src/util/mkmap_db.c 1 ['N/A'] 19 0 12 3 2 73 0 407 108
dict_cidr_open /src/postfix/postfix/src/util/dict_cidr.c 3 ['N/A', 'int', 'int'] 21 0 261 50 17 106 0 661 87
dict_pipe_open /src/postfix/postfix/src/util/dict_pipe.c 3 ['N/A', 'int', 'int'] 20 0 252 54 21 89 0 466 71
dict_load_file_xt /src/postfix/postfix/src/util/dict.c 2 ['N/A', 'N/A'] 14 0 90 21 7 80 2 481 68
dict_inline_open /src/postfix/postfix/src/util/dict_inline.c 3 ['N/A', 'int', 'int'] 19 0 264 55 23 87 0 509 58

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

Functions statically reachable by fuzzers
48.0%
280 / 585
Cyclomatic complexity statically reachable by fuzzers
61.0%
2399 / 3944

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_tok822.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=['vbuf_print', 'msg_vstream_print', 'printable_except', 'vstring_alloc', 'LLVMFuzzerTestOneInput', 'msg_output', 'msg_vstream_init']

fuzz_mime.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=['myfree', 'vstring_alloc', 'vstring_strncat', 'mime_state_update', 'msg_output', 'msg_vstream_init', 'LLVMFuzzerTestOneInput', 'myrealloc']

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
vbuf_print 150 70 46.66% ['fuzz_mime', 'fuzz_tok822']
vstream_fflush_some 88 37 42.04% ['fuzz_mime', 'fuzz_tok822']
mime_state_update 213 72 33.80% ['fuzz_mime']

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/postfix/postfix/src/util/sock_addr.c [] []
/src/postfix/postfix/src/util/timed_write.c [] []
/src/postfix/postfix/src/util/vbuf_print.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/dict_sockmap.c [] []
/src/postfix/postfix/src/global/mail_params.c [] []
/src/postfix/postfix/src/util/timed_read.c [] []
/src/postfix/postfix/src/global/mynetworks.c [] []
/src/postfix/postfix/src/util/sane_strtol.c [] []
/src/postfix/postfix/src/global/conv_time.c [] []
/src/postfix/postfix/src/util/msg_vstream.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/global/mail_conf_int.c [] []
/src/postfix/postfix/src/util/./parse_utf8_char.h ['fuzz_tok822', 'fuzz_mime'] []
/src/postfix/postfix/src/util/myaddrinfo.c [] []
/src/postfix/postfix/src/util/mask_addr.c [] []
/src/postfix/postfix/src/util/dict_pipe.c [] []
/src/postfix/postfix/src/util/msg_syslog.c [] []
/src/postfix/postfix/src/global/verp_sender.c [] []
/src/postfix/postfix/src/util/concatenate.c [] []
/src/postfix/postfix/src/global/compat_level.c [] []
/src/postfix/postfix/src/util/mkmap_db.c [] []
/src/postfix/postfix/src/util/dict_regexp.c [] []
/src/postfix/postfix/src/util/hex_quote.c [] []
/src/postfix/postfix/src/util/unix_connect.c [] []
/src/postfix/postfix/src/util/vstring_vstream.c [] []
/src/postfix/postfix/src/util/open_limit.c [] []
/src/postfix/postfix/src/global/mail_conf_str.c [] []
/src/postfix/postfix/src/util/base64_code.c [] []
/src/postfix/postfix/src/util/htable.c ['fuzz_mime'] []
/src/postfix/postfix/src/global/tok822_tree.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/global/mail_conf_bool.c [] []
/src/postfix/postfix/src/util/mac_parse.c [] []
/src/postfix/postfix/src/util/vstring.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/dict.c [] []
/src/postfix/postfix/src/util/non_blocking.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/hash_fnv.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/dict_union.c [] []
/src/postfix/postfix/src/util/ldseed.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/valid_utf8_hostname.c [] []
/src/postfix/postfix/src/global/header_opts.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/known_tcp_ports.c [] []
/src/postfix/postfix/src/util/argv.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/mac_midna.c [] []
/src/postfix/postfix/src/global/mail_conf_nbool.c [] []
/src/postfix/postfix/src/util/cidr_match.c [] []
/src/postfix/postfix/src/util/dict_stream.c [] []
/src/fuzz_mime.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/util/inet_addr_host.c [] []
/src/postfix/postfix/src/util/mvect.c [] []
/src/postfix/postfix/src/util/allascii.c [] []
/src/postfix/postfix/src/util/split_at.c [] []
/src/postfix/postfix/src/util/close_on_exec.c [] []
/src/postfix/postfix/src/util/poll_fd.c [] []
/src/postfix/postfix/src/global/been_here.c [] []
/src/postfix/postfix/src/util/host_port.c [] []
/src/postfix/postfix/src/util/inet_connect.c [] []
/src/fuzz_tok822.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/mkmap_fail.c [] []
/src/postfix/postfix/src/util/myflock.c [] []
/src/postfix/postfix/src/util/timed_connect.c [] []
/src/postfix/postfix/src/global/mime_state.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/util/safe_getenv.c [] []
/src/postfix/postfix/src/util/extpar.c [] []
/src/postfix/postfix/src/util/vstream.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/global/tok822_node.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/inet_addr_local.c [] []
/src/postfix/postfix/src/util/events.c [] []
/src/postfix/postfix/src/util/sane_connect.c [] []
/src/postfix/postfix/src/util/dict_db.c [] []
/src/postfix/postfix/src/global/is_header.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/util/auto_clnt.c [] []
/src/postfix/postfix/src/util/get_hostname.c [] []
/src/postfix/postfix/src/util/casefold.c [] []
/src/postfix/postfix/src/util/dict_alloc.c [] []
/src/postfix/postfix/src/util/ring.c [] []
/src/postfix/postfix/src/global/own_inet_addr.c [] []
/src/postfix/postfix/src/util/dict_static.c [] []
/src/postfix/postfix/src/util/dict_file.c [] []
/src/postfix/postfix/src/util/dict_tcp.c [] []
/src/postfix/postfix/src/util/normalize_ws.c [] []
/usr/include/x86_64-linux-gnu/bits/byteswap.h [] []
/src/postfix/postfix/src/util/printable.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/dict_utf8.c [] []
/src/postfix/postfix/src/util/vbuf.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/inet_windowsize.c [] []
/src/postfix/postfix/src/util/dict_surrogate.c [] []
/src/postfix/postfix/src/util/dict_cidr.c [] []
/src/postfix/postfix/src/util/argv_split.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/myrand.c [] []
/src/postfix/postfix/src/util/unsafe.c [] []
/src/postfix/postfix/src/util/split_qnameval.c [] []
/src/postfix/postfix/src/global/header_token.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/name_code.c [] []
/src/postfix/postfix/src/global/quote_822_local.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/global/config_known_tcp_ports.c [] []
/src/postfix/postfix/src/util/msg.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/dict_open.c [] []
/src/postfix/postfix/src/util/dict_fail.c [] []
/src/postfix/postfix/src/util/split_nameval.c [] []
/src/postfix/postfix/src/util/msg_output.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/netstring.c [] []
/src/postfix/postfix/src/util/dict_debug.c [] []
/src/postfix/postfix/src/util/inet_addr_list.c [] []
/src/postfix/postfix/src/global/mail_conf_time.c [] []
/src/postfix/postfix/src/util/logwriter.c [] []
/src/postfix/postfix/src/util/dict_ht.c [] []
/src/postfix/postfix/src/util/mystrtok.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/readlline.c [] []
/src/postfix/postfix/src/util/alldig.c [] []
/src/postfix/postfix/src/util/safe_open.c [] []
/src/postfix/postfix/src/util/balpar.c [] []
/src/postfix/postfix/src/util/dict_random.c [] []
/src/postfix/postfix/src/util/dict_inline.c [] []
/src/postfix/postfix/src/util/dict_unix.c [] []
/src/postfix/postfix/src/util/inet_proto.c [] []
/src/postfix/postfix/src/util/mac_expand.c [] []
/src/postfix/postfix/src/util/name_mask.c [] []
/src/postfix/postfix/src/util/trimblanks.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/valid_hostname.c [] []
/src/postfix/postfix/src/util/dict_env.c [] []
/src/postfix/postfix/src/global/tok822_parse.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/warn_stat.c [] []
/src/postfix/postfix/src/util/argv_splitq.c [] []
/src/postfix/postfix/src/util/sane_basename.c [] []
/src/postfix/postfix/src/util/valid_utf8_string.c [] []
/src/postfix/postfix/src/global/mail_conf_long.c [] []
/src/postfix/postfix/src/util/argv_split_at.c [] []
/src/postfix/postfix/src/util/strcasecmp_utf8.c [] []
/src/postfix/postfix/src/util/mystrerror.c ['fuzz_tok822', 'fuzz_mime'] []
/src/postfix/postfix/src/global/mail_conf.c [] []
/src/postfix/postfix/src/util/mymalloc.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/doze.c [] []
/src/postfix/postfix/src/util/dict_thash.c [] []
/src/postfix/postfix/src/util/lowercase.c ['fuzz_mime'] []

Directories in report

Directory
/src/postfix/postfix/src/util/./
/usr/include/x86_64-linux-gnu/bits/
/src/postfix/postfix/src/util/
/src/postfix/postfix/src/global/
/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_tok822 fuzzerLogFile-0-ePN4jWCvEJ.data fuzzerLogFile-0-ePN4jWCvEJ.data.yaml fuzz_tok822.covreport
fuzz_mime fuzzerLogFile-0-6OdsNCETP4.data fuzzerLogFile-0-6OdsNCETP4.data.yaml fuzz_mime.covreport