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: 2026-07-16

Project overview: postfix

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
15.0%
96 / 621
Cyclomatic complexity statically reachable by fuzzers
22.0%
929 / 4205
Runtime code coverage of functions
9.0%
55 / 621

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_tok822 fuzz_tok822.c 67 81 18 16 1452 559 fuzz_tok822.c
fuzz_mime fuzz_mime.c 100 589 22 25 1766 720 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 88 35.7%
gold [1:9] 7 2.84%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 151 61.3%
All colors 246 100

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 62 vbuf_print call site: 00062 msg_panic
15 108 msg_vstream_print call site: 00108 vstream_fflush_delayed
9 32 printable_except call site: 00032 mystrdup
4 10 vstring_alloc call site: 00010 msg_panic
4 45 vbuf_print call site: 00045 msg_warn
3 1 LLVMFuzzerTestOneInput call site: 00001 msg_panic
3 93 msg_output_push call site: 00093 myrealloc
2 42 vbuf_print call site: 00042 msg_panic
2 55 vbuf_print call site: 00055 msg_panic
2 97 myfree call site: 00097 mymalloc
2 103 msg_vstream_init call site: 00103 msg_panic
2 124 vstream_fflush call site: 00124 sleep

Runtime coverage analysis

Covered functions
48
Functions that are reachable but not covered
23
Reachable functions
67
Percentage of reachable functions covered
65.67%
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/vstream.c 5
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/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 0 260 88.4%
gold [1:9] 2 0.68%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 32 10.8%
All colors 294 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
118 139 vstring_strncat call site: 00139 header_opts_find
79 16 vstring_alloc call site: 00016 msg_panic
24 262 mime_state_update call site: 00262 mime_state_pop
20 96 vstring_alloc call site: 00096 vstream_fprintf
5 4 msg_output_push call site: 00004 msg_panic
5 10 msg_vstream_init call site: 00010 msg_panic
3 117 msg_output_push call site: 00117 myrealloc
2 121 myfree call site: 00121 mymalloc
2 136 LLVMFuzzerTestOneInput call site: 00136 mime_state_update
1 125 myrealloc call site: 00125 msg_fatal
1 290 vstring_free call site: 00290 mime_state_pop

Runtime coverage analysis

Covered functions
21
Functions that are reachable but not covered
81
Reachable functions
100
Percentage of reachable functions covered
19.0%
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.
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/vstream.c 5
postfix/postfixutil/msg_output.c 2
postfix/postfixutil/vstring.c 8
postfix/postfixutil/msg.c 8
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 22 111 0 731 405
dict_tcp_lookup /src/postfix/postfix/src/util/dict_tcp.c 2 ['N/A', 'N/A'] 14 0 351 65 23 112 0 726 304
nbdb_dict_btree_open /src/postfix/postfix/src/global/nbdb_redirect.c 3 ['N/A', 'int', 'int'] 17 0 12 3 2 110 0 713 244
dict_sockmap_lookup /src/postfix/postfix/src/util/dict_sockmap.c 2 ['N/A', 'N/A'] 15 0 277 54 22 91 0 549 167
get_mail_conf_time_table /src/postfix/postfix/src/global/mail_conf_time.c 1 ['N/A'] 16 0 43 9 4 90 2 547 158
mynetworks_core /src/postfix/postfix/src/global/mynetworks.c 1 ['N/A'] 15 0 385 79 20 120 2 624 155
mkmap_btree_open /src/postfix/postfix/src/util/mkmap_db.c 1 ['N/A'] 20 0 12 3 2 75 0 435 107
dict_cidr_open /src/postfix/postfix/src/util/dict_cidr.c 3 ['N/A', 'int', 'int'] 21 0 261 50 17 108 0 687 88
nbdb_util_init /src/postfix/postfix/src/global/nbdb_util.c 1 ['N/A'] 11 0 103 25 9 82 2 466 68
dict_thash_open /src/postfix/postfix/src/util/dict_thash.c 3 ['N/A', 'int', 'int'] 19 0 520 110 39 85 0 529 58

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

Functions statically reachable by fuzzers
48.0%
300 / 621
Cyclomatic complexity statically reachable by fuzzers
62.0%
2593 / 4205

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_push', 'myfree']

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=['vstring_strncat', 'vstring_alloc', 'mime_state_update', 'msg_output_push', 'msg_vstream_init', 'myfree', '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_tok822', 'fuzz_mime']
vstream_fflush_some 88 37 42.04% ['fuzz_tok822', 'fuzz_mime']
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/./parse_utf8_char.h ['fuzz_tok822', 'fuzz_mime'] []
/src/postfix/postfix/src/global/conv_time.c [] []
/src/postfix/postfix/src/util/sock_addr.c [] []
/src/postfix/postfix/src/global/mynetworks.c [] []
/src/postfix/postfix/src/global/tok822_tree.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/close_on_exec.c [] []
/src/postfix/postfix/src/util/get_hostname.c [] []
/src/postfix/postfix/src/util/msg_output.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/unsafe.c [] []
/src/postfix/postfix/src/util/dict_static.c [] []
/src/postfix/postfix/src/util/warn_stat.c [] []
/src/postfix/postfix/src/global/header_opts.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/ring.c [] []
/src/postfix/postfix/src/util/valid_hostname.c [] []
/src/postfix/postfix/src/util/inet_proto.c [] []
/src/postfix/postfix/src/util/dict_db.c [] []
/src/postfix/postfix/src/util/dict_stream.c [] []
/src/postfix/postfix/src/global/mail_conf_long.c [] []
/src/postfix/postfix/src/util/split_qnameval.c [] []
/src/postfix/postfix/src/util/inet_addr_list.c [] []
/src/postfix/postfix/src/util/msg_vstream.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/attr_print0.c [] []
/src/postfix/postfix/src/util/open_limit.c [] []
/src/postfix/postfix/src/util/cidr_match.c [] []
/src/postfix/postfix/src/util/dict_inline.c [] []
/src/postfix/postfix/src/util/inet_connect.c [] []
/src/postfix/postfix/src/global/tok822_node.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/global/mail_conf_bool.c [] []
/src/postfix/postfix/src/util/poll_fd.c [] []
/src/fuzz_mime.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/util/htable.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/dict_file.c [] []
/src/postfix/postfix/src/util/dict_utf8.c [] []
/src/postfix/postfix/src/util/dict_union.c [] []
/src/postfix/postfix/src/global/header_token.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/mask_addr.c [] []
/src/postfix/postfix/src/util/argv_splitq.c [] []
/src/postfix/postfix/src/global/mail_params.c [] []
/src/postfix/postfix/src/global/nbdb_redirect.c [] []
/src/postfix/postfix/src/util/safe_open.c [] []
/src/postfix/postfix/src/util/mac_midna.c [] []
/src/postfix/postfix/src/util/dict_unix.c [] []
/src/postfix/postfix/src/util/ldseed.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/safe_getenv.c [] []
/src/postfix/postfix/src/util/timed_connect.c [] []
/src/postfix/postfix/src/util/events.c [] []
/src/postfix/postfix/src/util/balpar.c [] []
/src/postfix/postfix/src/global/mime_state.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/util/mystrerror.c ['fuzz_tok822', 'fuzz_mime'] []
/src/postfix/postfix/src/util/msg_syslog.c [] []
/src/postfix/postfix/src/util/dict_cidr.c [] []
/src/postfix/postfix/src/util/dict_env.c [] []
/src/postfix/postfix/src/util/vbuf.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/usr/include/x86_64-linux-gnu/bits/byteswap.h [] []
/src/postfix/postfix/src/util/unix_connect.c [] []
/src/postfix/postfix/src/util/dict_fail.c [] []
/src/postfix/postfix/src/util/known_tcp_ports.c [] []
/src/postfix/postfix/src/util/mkmap_db.c [] []
/src/postfix/postfix/src/global/mail_conf_time.c [] []
/src/postfix/postfix/src/util/timed_read.c [] []
/src/postfix/postfix/src/util/myrand.c [] []
/src/postfix/postfix/src/util/vbuf_print.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/vstream.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/alldig.c [] []
/src/postfix/postfix/src/util/wrap_netdb.c [] []
/src/postfix/postfix/src/util/dict_random.c [] []
/src/postfix/postfix/src/util/dict_sockmap.c [] []
/src/postfix/postfix/src/util/valid_utf8_hostname.c [] []
/src/postfix/postfix/src/util/concatenate.c [] []
/src/postfix/postfix/src/util/non_blocking.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/split_nameval.c [] []
/src/postfix/postfix/src/util/base64_code.c [] []
/src/fuzz_tok822.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/allascii.c [] []
/src/postfix/postfix/src/util/mac_parse.c [] []
/src/postfix/postfix/src/global/is_header.c ['fuzz_mime'] ['fuzz_mime']
/src/postfix/postfix/src/global/verp_sender.c [] []
/src/postfix/postfix/src/util/inet_windowsize.c [] []
/src/postfix/postfix/src/global/quote_822_local.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/netstring.c [] []
/src/postfix/postfix/src/util/mkmap_fail.c [] []
/src/postfix/postfix/src/util/dict_open.c [] []
/src/postfix/postfix/src/global/nbdb_util.c [] []
/src/postfix/postfix/src/util/dict_thash.c [] []
/src/postfix/postfix/src/util/extpar.c [] []
/src/postfix/postfix/src/util/logwriter.c [] []
/src/postfix/postfix/src/util/inet_addr_host.c [] []
/src/postfix/postfix/src/util/hash_fnv.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/lowercase.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/mystrtok.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/mymalloc.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/mvect.c [] []
/src/postfix/postfix/src/util/dict_alloc.c [] []
/src/postfix/postfix/src/util/sane_basename.c [] []
/src/postfix/postfix/src/util/hex_quote.c [] []
/src/postfix/postfix/src/util/printable.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/name_mask.c [] []
/src/postfix/postfix/src/util/dict_surrogate.c [] []
/src/postfix/postfix/src/util/myflock.c [] []
/src/postfix/postfix/src/util/trimblanks.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/myaddrinfo.c [] []
/src/postfix/postfix/src/util/timed_write.c [] []
/src/postfix/postfix/src/global/mail_conf.c [] []
/src/postfix/postfix/src/util/vstring.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822', 'fuzz_mime']
/src/postfix/postfix/src/util/doze.c [] []
/src/postfix/postfix/src/util/auto_clnt.c [] []
/src/postfix/postfix/src/util/casefold.c [] []
/src/postfix/postfix/src/util/sane_strtol.c [] []
/src/postfix/postfix/src/global/mail_conf_str.c [] []
/src/postfix/postfix/src/util/inet_addr_local.c [] []
/src/postfix/postfix/src/util/dict_ht.c [] []
/src/postfix/postfix/src/util/name_code.c [] []
/src/postfix/postfix/src/util/sane_connect.c [] []
/src/postfix/postfix/src/global/been_here.c [] []
/src/postfix/postfix/src/util/msg.c ['fuzz_tok822', 'fuzz_mime'] ['fuzz_tok822']
/src/postfix/postfix/src/util/attr_scan0.c [] []
/src/postfix/postfix/src/util/argv.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/readlline.c [] []
/src/postfix/postfix/src/util/host_port.c [] []
/src/postfix/postfix/src/util/dict_tcp.c [] []
/src/postfix/postfix/src/util/strcasecmp_utf8.c [] []
/src/postfix/postfix/src/global/config_known_tcp_ports.c [] []
/src/postfix/postfix/src/global/tok822_parse.c ['fuzz_tok822'] ['fuzz_tok822']
/src/postfix/postfix/src/util/argv_split.c ['fuzz_mime'] []
/src/postfix/postfix/src/util/mac_expand.c [] []
/src/postfix/postfix/src/global/mail_conf_nbool.c [] []
/src/postfix/postfix/src/util/dict_pipe.c [] []
/src/postfix/postfix/src/util/argv_split_at.c [] []
/src/postfix/postfix/src/global/compat_level.c [] []
/src/postfix/postfix/src/global/mail_conf_int.c [] []
/src/postfix/postfix/src/global/nbdb_clnt.c [] []
/src/postfix/postfix/src/util/dict.c [] []
/src/postfix/postfix/src/util/normalize_ws.c [] []
/src/postfix/postfix/src/util/vstring_vstream.c [] []
/src/postfix/postfix/src/util/dict_regexp.c [] []
/src/postfix/postfix/src/util/valid_utf8_string.c [] []
/src/postfix/postfix/src/util/dict_debug.c [] []
/src/postfix/postfix/src/global/own_inet_addr.c [] []
/src/postfix/postfix/src/util/split_at.c [] []

Directories in report

Directory
/src/
/src/postfix/postfix/src/global/
/src/postfix/postfix/src/util/
/src/postfix/postfix/src/util/./
/usr/include/x86_64-linux-gnu/bits/

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-y1Msf47Q6I.data fuzzerLogFile-0-y1Msf47Q6I.data.yaml fuzz_tok822.covreport
fuzz_mime fuzzerLogFile-0-DuA059x7wY.data fuzzerLogFile-0-DuA059x7wY.data.yaml fuzz_mime.covreport