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

Table of contents

Project overview: htslib
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: hts_open_fuzzer
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Runtime coverage analysis
Complex functions with low coverage
Files and Directories in report
Files in report
Directories in report
Metadata section
Function call coverage
Function in each files in report
Report generation date: 2023-01-17

Project overview: htslib

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
60.4%
1089/1803
Cyclomatic complexity statically reachable by fuzzers
67.96%
11300/16627
Functions covered at runtime
492

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
hts_open_fuzzer /src/htslib/test/fuzz/hts_open_fuzzer.c 1090 714 20 72 29516 11303 hts_open_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 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: hts_open_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 3348 66.4%
gold [1:9] 241 4.78%
yellow [10:29] 68 1.34%
greenyellow [30:49] 43 0.85%
lawngreen 50+ 1339 26.5%
All colors 5039 100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity Unique Reachable Complexities Unique Reachable Functions All non-covered Complexity All Reachable Complexity Function Name Function Callsite Blocked Branch
6470 6470 1 :

['cram_write_eof_block']

6496 7375 cram_close call site /src/htslib/cram/cram_io.c:5504
6365 6365 2 :

['cram_update_curr_slice', 'cram_flush_container_mt']

17031 18109 cram_close call site /src/htslib/cram/cram_io.c:5475
4170 4170 4 :

['cram_flush_result', 'hts_tpool_process_destroy', 'pthread_mutex_destroy', 'hts_tpool_process_flush']

10666 11545 cram_close call site /src/htslib/cram/cram_io.c:5486
2787 2787 1 :

['hts_process_opts']

2795 2795 hts_hopen call site /src/htslib/hts.c:1503
2701 2719 5 :

['strerror', '__errno_location', 'hts_opt_apply', 'hts_log', 'hclose_abruptly']

2701 2719 hts_open_format call site /src/htslib/hts.c:900
1023 1079 10 :

['hts_idx_push', 'bcf_seqname_safe', 'float_to_le.1852', 'u32_to_le.1813', 'i32_to_le.1812', 'hts_log', 'u16_to_le.1814', 'bcf1_sync', 'bgzf_write', 'bcf_strerror']

1023 1079 bcf_write call site /src/htslib/vcf.c:1970
734 734 1 :

['bcf_hdr_append']

734 734 bcf_hdr_init call site /src/htslib/vcf.c:1209
630 640 10 :

['sam_hdr_tid2name', 'sam_hdr_find_tag_id', 'cram_get_block_by_id', 'ks_free.2171', 'hts_md5_update', 'hts_md5_destroy', 'md5_print', 'memcmp', 'hts_md5_init', 'hts_md5_final']

3627 3917 cram_decode_slice call site /src/htslib/cram/cram_decode.c:2395
410 7682 19 :

['free', 'cram_read_container', 'hts_tpool_process_len', 'cram_seek', 'cram_free_slice', 'pthread_mutex_unlock', 'hts_log', 'cram_free_container', 'sam_hrecs_sort_order', 'hts_tpool_result_data', 'cram_decode_compression_header', 'cram_read_block', 'hts_tpool_next_result_wait', 'pthread_mutex_lock', 'hts_tpool_delete_result', 'cram_decode_slice_mt', 'cram_read_slice', 'hts_tpool_process_qsize', 'hts_tpool_process_empty']

410 7682 cram_next_slice call site /src/htslib/cram/cram_decode.c:3228
394 394 2 :

['bgzf_flush_try', 'bgzf_write']

717 767 sam_write1 call site /src/htslib/sam.c:4462
394 394 2 :

['bgzf_flush_try', 'bgzf_write']

535 545 vcf_write call site /src/htslib/vcf.c:3444
387 387 2 :

['bgzf_flush', 'bgzf_write']

387 387 vcf_hdr_write call site /src/htslib/vcf.c:2267

Runtime coverage analysis

Covered functions
492
Functions that are reachable but not covered
637
Reachable functions
1090
Percentage of reachable functions covered
41.56%
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
/src/htslib/test/fuzz/hts_open_fuzzer.c 4
/src/htslib/hfile.c 38
/src/htslib/./textutils_internal.h 12
/src/htslib/hts.c 52
/src/htslib/./htslib/khash.h 1
/src/htslib/hfile_libcurl.c 9
/src/htslib/kstring.c 6
/src/htslib/./htslib/kstring.h 16
/src/htslib/hfile_gcs.c 1
/src/htslib/hfile_s3.c 1
/src/htslib/hfile_s3_write.c 4
/src/htslib/./htslib/hts.h 4
/src/htslib/./hts_internal.h 1
/src/htslib/multipart.c 5
/src/htslib/textutils.c 8
/src/htslib/./htslib/hfile.h 8
/src/htslib/bgzf.c 66
/src/htslib/cram/cram_io.c 99
/src/htslib/cram/../htslib/hfile.h 5
/src/htslib/cram/../htscodecs/htscodecs/varint.h 11
/src/htslib/cram/cram_io.h 10
/src/htslib/cram/cram_structs.h 23
/src/htslib/cram/../header.h 4
/src/htslib/cram/string_alloc.c 6
/src/htslib/cram/cram_stats.c 5
/src/htslib/htscodecs/htscodecs/rANS_static.c 6
/src/htslib/htscodecs/htscodecs/utils.c 5
/src/htslib/htscodecs/htscodecs/rANS_byte.h 11
/src/htslib/htscodecs/htscodecs/fqzcomp_qual.c 16
/src/htslib/htscodecs/htscodecs/varint.h 3
/src/htslib/htscodecs/htscodecs/c_simple_model.h 10
/src/htslib/htscodecs/htscodecs/c_range_coder.h 11
/src/htslib/htscodecs/htscodecs/rANS_static4x16pr.c 10
/src/htslib/htscodecs/htscodecs/utils.h 5
/src/htslib/htscodecs/htscodecs/pack.c 3
/usr/local/lib/clang/15.0.0/include/cpuid.h 1
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_avx512.c 5
/src/htslib/htscodecs/htscodecs/rANS_static16_int.h 14
/src/htslib/htscodecs/htscodecs/rANS_word.h 9
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_avx2.c 6
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_sse4.c 4
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr.c 4
/src/htslib/htscodecs/htscodecs/rle.c 3
/src/htslib/htscodecs/htscodecs/arith_dynamic.c 11
/src/htslib/htscodecs/htscodecs/tokenise_name3.c 33
/src/htslib/htscodecs/htscodecs/pooled_alloc.h 4
/src/htslib/sam.c 77
/src/htslib/header.c 38
/src/htslib/./header.h 11
/src/htslib/cram/pooled_alloc.c 6
/src/htslib/./cram/../htslib/khash.h 1
/src/htslib/cram/mFILE.c 12
/src/htslib/thread_pool.c 29
/src/htslib/./htslib/hts_endian.h 16
/src/htslib/cram/../htslib/khash.h 1
/src/htslib/cram/cram_index.c 6
/src/htslib/cram/cram_decode.c 23
/src/htslib/faidx.c 12
/src/htslib/./sam_internal.h 3
/src/htslib/./cram/../htslib/sam.h 4
/src/htslib/./cram/cram_io.h 1
/src/htslib/hts_expr.c 21
/src/htslib/cram/cram_encode.c 38
/src/htslib/cram/open_trace_file.c 6
/src/htslib/md5.c 7
/src/htslib/cram/../textutils_internal.h 1
/src/htslib/cram/../sam_internal.h 1
/src/htslib/cram/cram_codecs.c 4
/src/htslib/./htslib/hts_expr.h 4
/src/htslib/vcf.c 73
/src/htslib/tbx.c 5
/src/htslib/./htslib/vcf.h 11

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
s3_vopen /src/htslib/hfile_s3.c 3 ['char *', 'char *', 'struct.__va_list_tag *'] 6 0 52 6 3 143 0 759 342
vhopen_libcurl /src/htslib/hfile_libcurl.c 3 ['char *', 'char *', 'struct.__va_list_tag *'] 7 0 61 9 4 146 0 786 323
bam_mplp_auto /src/htslib/sam.c 5 ['struct.bam_mplp_s *', 'int *', 'int *', 'int *', 'struct.bam_pileup1_t **'] 6 0 72 10 4 32 0 306 255
bcf_index_build /src/htslib/vcf.c 2 ['char *', 'int '] 14 0 20 3 2 943 0 9400 252
cram_codec_decoder2encoder /src/htslib/cram/cram_codecs.c 2 ['struct.cram_fd.697 *', 'struct.cram_codec.701 *'] 4 0 655 98 29 48 1 259 229
sam_itr_regarray /src/htslib/sam.c 4 ['struct.hts_idx_t *', 'struct.sam_hdr_t *', 'char **', 'int '] 14 0 132 19 8 636 0 5899 210
sam_itr_queryi /src/htslib/sam.c 4 ['struct.hts_idx_t *', 'int ', 'size_t ', 'size_t '] 14 0 68 8 4 685 0 6254 134
sam_hdr_remove_lines /src/htslib/header.c 4 ['struct.sam_hdr_t *', 'char *', 'char *', 'char *'] 7 0 330 51 21 74 0 670 108
cram_huffman_decode_init /src/htslib/cram/cram_codecs.c 7 ['struct.cram_block_compression_hdr.670 *', 'char *', 'int ', 'int ', 'int ', 'int ', 'struct.varint_vec.698 *'] 1 0 747 107 39 17 0 111 89
bcf_hdr_subset /src/htslib/vcf.c 4 ['struct.bcf_hdr_t *', 'int ', 'char **', 'int *'] 6 0 392 49 18 83 0 640 86

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

Functions statically reachable by fuzzers
73.16%
1319/1803
Cyclomatic complexity statically reachable by fuzzers
79.98%
13299 / 16627

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 Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

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
bgzf_read_block 205 109 53.17% ['hts_open_fuzzer']
bgzf_close 42 21 50.0% ['hts_open_fuzzer']
bgzf_check_EOF 34 9 26.47% ['hts_open_fuzzer']
cache_block 38 7 18.42% ['hts_open_fuzzer']
cram_dependent_data_series 227 20 8.810% ['hts_open_fuzzer']
cram_decode_slice 533 104 19.51% ['hts_open_fuzzer']
cram_get_seq 45 12 26.66% ['hts_open_fuzzer']
cram_drain_rqueue 50 4 8.0% ['hts_open_fuzzer']
cram_decode_slice_xref 110 7 6.363% ['hts_open_fuzzer']
cram_next_slice 184 94 51.08% ['hts_open_fuzzer']
cram_first_slice 42 21 50.0% ['hts_open_fuzzer']
cram_uncompress_block 147 76 51.70% ['hts_open_fuzzer']
cram_free_container 46 19 41.30% ['hts_open_fuzzer']
cram_close 74 37 50.0% ['hts_open_fuzzer']
cram_set_voption 215 10 4.651% ['hts_open_fuzzer']
sam_hdr_count_lines 35 13 37.14% ['hts_open_fuzzer']
sam_hrecs_find_type_id 53 13 24.52% ['hts_open_fuzzer']
hseek 36 16 44.44% ['hts_open_fuzzer']
hts_idx_check_local 102 40 39.21% ['hts_open_fuzzer']
hts_idx_load3 32 7 21.87% ['hts_open_fuzzer']
format_category 34 9 26.47% ['hts_open_fuzzer']
idx_find_and_load 48 10 20.83% ['hts_open_fuzzer']
rans_uncompress_O1 161 63 39.13% ['hts_open_fuzzer']
decode_name 145 45 31.03% ['hts_open_fuzzer']
unstripe 54 26 48.14% ['hts_open_fuzzer']
sam_hdr_dup 46 17 36.95% ['hts_open_fuzzer']
sam_state_destroy 81 5 6.172% ['hts_open_fuzzer']
sam_write1 127 16 12.59% ['hts_open_fuzzer']
sam_read1_sam 74 17 22.97% ['hts_open_fuzzer']
index_load 38 13 34.21% ['hts_open_fuzzer']
bcf_write 44 10 22.72% ['hts_open_fuzzer']
vcf_hdr_read 81 35 43.20% ['hts_open_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/htslib/cram/../htscodecs/htscodecs/varint.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./sam_internal.h ['hts_open_fuzzer'] []
/src/htslib/cram/cram_codecs.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/hts_endian.h ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/rle.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/kstring.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_byte.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/tbx.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_index.c ['hts_open_fuzzer'] []
/src/htslib/./hts_time_funcs.h [] []
/src/htslib/faidx.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/rANS_static.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/region.c [] []
/src/htslib/htscodecs/htscodecs/htscodecs.c [] []
/src/htslib/multipart.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/fqzcomp_qual.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/thread_pool.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/pack.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/../sam_internal.h ['hts_open_fuzzer'] []
/src/htslib/cram/open_trace_file.c ['hts_open_fuzzer'] []
/src/htslib/./htslib/khash.h ['hts_open_fuzzer'] []
/src/htslib/vcf.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_io.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/utils.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/mFILE.c ['hts_open_fuzzer'] []
/src/htslib/hts.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./textutils_internal.h ['hts_open_fuzzer'] []
/usr/local/lib/clang/15.0.0/include/cpuid.h ['hts_open_fuzzer'] []
/src/htslib/cram/../header.h ['hts_open_fuzzer'] []
/src/htslib/./cram/cram_io.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/hfile_libcurl.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/../htslib/hfile.h ['hts_open_fuzzer'] []
/src/htslib/sam.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/hts_expr.h ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/arith_dynamic.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/../htslib/hts_endian.h [] []
/src/htslib/./cram/../htslib/khash.h ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/rANS_static4x16pr.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/tokenise_name3.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/vcf.h ['hts_open_fuzzer'] []
/src/htslib/cram/cram_io.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/string_alloc.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/hfile_s3_write.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/hfile_s3.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_avx2.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_structs.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/pooled_alloc.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./hts_internal.h ['hts_open_fuzzer'] []
/src/htslib/hfile.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_encode.c ['hts_open_fuzzer'] []
/src/htslib/./htslib/hfile.h ['hts_open_fuzzer'] []
/src/htslib/cram/cram_codecs.h [] []
/src/htslib/bgzf.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_decode.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/textutils.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/cram_stats.c ['hts_open_fuzzer'] []
/src/htslib/hfile_gcs.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/hts.h ['hts_open_fuzzer'] []
/src/htslib/header.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_word.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/varint.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./header.h ['hts_open_fuzzer'] []
/src/htslib/md5.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/utils.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_static16_int.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_avx512.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/c_simple_model.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/hts_expr.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/cram/../textutils_internal.h ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr_sse4.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/kstring.h ['hts_open_fuzzer'] []
/src/htslib/test/fuzz/hts_open_fuzzer.c ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/htscodecs/htscodecs/rANS_static32x16pr.c ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/pooled_alloc.h ['hts_open_fuzzer'] ['hts_open_fuzzer']
/src/htslib/./htslib/khash_str2int.h [] []
/src/htslib/./cram/../htslib/sam.h ['hts_open_fuzzer'] []
/src/htslib/htscodecs/htscodecs/c_range_coder.h ['hts_open_fuzzer'] ['hts_open_fuzzer']

Directories in report

Directory
/src/htslib/./cram/
/src/htslib/
/src/htslib/./htslib/
/src/htslib/htscodecs/htscodecs/
/src/htslib/cram/../
/src/htslib/cram/../htscodecs/htscodecs/
/src/htslib/test/fuzz/
/src/htslib/cram/../htslib/
/src/htslib/cram/
/src/htslib/./
/src/htslib/./cram/../htslib/
/usr/local/lib/clang/15.0.0/include/

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
hts_open_fuzzer fuzzerLogFile-0-PrrVoAaTgI.data fuzzerLogFile-0-PrrVoAaTgI.data.yaml hts_open_fuzzer.covreport

Function call coverage

This section shows a chosen list of functions / methods calls and their relative coverage information. By static analysis of the target project code, all of these function call and their caller information, including the source file or class and line number that initiate the call are captured. The caller source code file or class and the line number are shown in column 2 while column 1 is the function name of that selected functions or methods call. Each occurrent of the target function call will occuply a separate row. Column 3 of each row indicate if the target function calls is statically unreachable.Column 4 lists all fuzzers (or no fuzzers at all) that have covered that particular system call in dynamic fuzzing. Those functions with low to no reachability and dynamic hit count indicate missed fuzzing logic to fuzz and track for possible code injection sinks.

Function in each files in report

Target sink Callsite location Reached by fuzzer