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

Table of contents

Project overview: p11-kit
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: rpc_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/rpc_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: 2026-01-10

Project overview: p11-kit

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
3.0%
202 / 8031
Cyclomatic complexity statically reachable by fuzzers
7.00%
1986 / 27645
Runtime code coverage of functions
1.0%
104 / 8031

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
rpc_fuzzer ./fuzz/rpc_fuzzer.c 227 7896 8 12 5729 2038 rpc_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: rpc_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 0 878 77.0%
gold [1:9] 79 6.92%
yellow [10:29] 106 9.29%
greenyellow [30:49] 5 0.43%
lawngreen 50+ 72 6.31%
All colors 1140 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
253 796 rpc_C_UnwrapKey call site: 00796 rpc_C_DeriveKey
170 219 p11_rpc_buffer_get_uint64 call site: 00219 rpc_C_GetMechanismList
106 679 rpc_C_VerifyInit call site: 00679 rpc_C_WrapKey
69 414 rpc_C_CreateObject call site: 00414 rpc_C_GetAttributeValue
41 630 rpc_C_SignInit call site: 00630 rpc_C_SignRecoverInit
31 591 rpc_C_DigestInit call site: 00591 rpc_C_Digest
30 139 rpc_C_Initialize call site: 00139 rpc_C_GetInfo
29 521 proto_read_mechanism call site: 00521 rpc_C_Encrypt
26 558 rpc_C_DecryptInit call site: 00558 rpc_C_Decrypt
19 490 rpc_C_FindObjectsInit call site: 00490 rpc_C_EncryptInit
17 176 p11_rpc_buffer_add_uint64 call site: 00176 rpc_C_GetSlotList
16 196 p11_rpc_message_alloc_extra call site: 00196 rpc_C_GetSlotInfo

Runtime coverage analysis

Covered functions
105
Functions that are reachable but not covered
151
Reachable functions
227
Percentage of reachable functions covered
33.48%
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/rpc_fuzzer.c 1
common/mock.c 4
common/library.c 5
common/debug.c 4
common/compat.c 1
common/buffer.c 7
p11-kit/virtual.c 1
p11-kit/rpc-server.c 110
common/message.c 3
p11-kit/rpc-message.c 32
common/dict.c 9
common/attrs.c 9

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
p11_kit_remote_serve_tokens /src/p11-kit/p11-kit/rpc-server.c 5 ['N/A', 'size_t', 'N/A', 'int', 'int'] 14 0 546 110 36 454 0 3420 1447
log_C_GetAttributeValue /src/p11-kit/p11-kit/log.c 5 ['N/A', 'size_t', 'size_t', 'N/A', 'size_t'] 7 0 94 9 3 42 0 329 277
p11_kit_uri_format /src/p11-kit/p11-kit/uri.c 3 ['N/A', 'int', 'N/A'] 7 0 516 134 36 30 0 138 83

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

Functions statically reachable by fuzzers
6.0%
445 / 8031
Cyclomatic complexity statically reachable by fuzzers
13.0%
3705 / 27645

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/rpc_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_C_UnwrapKey', 'p11_rpc_buffer_get_uint64', 'rpc_C_VerifyInit', 'rpc_C_CreateObject', 'rpc_C_SignInit', 'rpc_C_DigestInit', 'rpc_C_Initialize', 'proto_read_mechanism', 'rpc_C_DecryptInit', 'rpc_C_FindObjectsInit']

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
parse_environ_flags 38 12 31.57% ['rpc_fuzzer']
p11_dict_set 33 15 45.45% ['rpc_fuzzer']
mock_C_Initialize 59 29 49.15% ['rpc_fuzzer']
p11_rpc_server_handle 139 40 28.77% ['rpc_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/p11-kit/common/dict.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/common/mock.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/common/debug.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/p11-kit/uri.c [] []
/src/p11-kit/p11-kit/iter.c [] []
/src/p11-kit/common/array.c [] []
/src/p11-kit/p11-kit/filter.c [] []
/src/p11-kit/p11-kit/util.c [] []
/src/p11-kit/p11-kit/modules.c [] []
/src/p11-kit/p11-kit/rpc-transport.c [] []
/src/p11-kit/common/constants.c [] []
/src/p11-kit/p11-kit/rpc-message.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/p11-kit/proxy.c [] []
/src/p11-kit/common/message.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/p11-kit/log.c [] []
/src/p11-kit/./p11-kit/virtual-stack-generated.h [] []
/src/p11-kit/./p11-kit/virtual-base-generated.h [] []
/src/p11-kit/common/lexer.c [] []
/src/p11-kit/p11-kit/rpc-server.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/common/hash.c [] []
/src/p11-kit/p11-kit/conf.c [] []
/src/p11-kit/p11-kit/messages.c [] []
/src/p11-kit/./p11-kit/proxy-generated.h [] []
/src/p11-kit/p11-kit/pin.c [] []
/src/p11-kit/common/vsock.c [] []
/src/p11-kit/common/compat.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/common/path.c [] []
/src/p11-kit/common/buffer.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/common/argv.c [] []
/src/p11-kit/./p11-kit/virtual-ffi-generated.h [] []
/src/p11-kit/p11-kit/virtual.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/p11-kit/rpc-client.c [] []
/src/p11-kit/common/attrs.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/./p11-kit/virtual-fixed-closures.h [] []
/src/p11-kit/common/url.c [] []
/src/p11-kit/common/library.c ['rpc_fuzzer'] ['rpc_fuzzer']
/src/p11-kit/./fuzz/rpc_fuzzer.c ['rpc_fuzzer'] []

Directories in report

Directory
/src/p11-kit/./fuzz/
/src/p11-kit/common/
/src/p11-kit/p11-kit/
/src/p11-kit/./p11-kit/

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
rpc_fuzzer fuzzerLogFile-0-EExlF4g1fA.data fuzzerLogFile-0-EExlF4g1fA.data.yaml rpc_fuzzer.covreport