High level conclusions

Fuzzers reach 66.30% code coverage.

Fuzzers reach 55.52% of cyclomatic complexity.

Fuzzers reach 60.43% of all functions.

Fuzzer round_trip_frame_uncompressed_fuzzer is blocked:

The runtime code coverage of round_trip_frame_uncompressed_fuzzer covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer round_trip_hc_fuzzer is blocked:

The runtime code coverage of round_trip_hc_fuzzer covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer round_trip_fuzzer is blocked:

The runtime code coverage of round_trip_fuzzer covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer round_trip_frame_fuzzer is blocked:

The runtime code coverage of round_trip_frame_fuzzer covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Reachability and coverage overview

Functions statically reachable by fuzzers

165 / 273

Cyclomatic complexity statically reachable by fuzzers

3373 / 6075

Runtime code coverage of functions

181 / 273

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.

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: round_trip_frame_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	338	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	338	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
337	0	EP	call site: 00000	FUZZ_decompressFrame

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

100

Reachable functions

100

Percentage of reachable functions covered

0.0%

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
ossfuzz/round_trip_frame_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	8
lib/lz4.c	21
lib/lz4frame.c	34
lib/lz4hc.c	19
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	1

Fuzzer: round_trip_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	185	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	185	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
184	0	EP	call site: 00000	LZ4_compress_default

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

35

Reachable functions

35

Percentage of reachable functions covered

0.0%

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
ossfuzz/round_trip_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4.c	25

Fuzzer: round_trip_hc_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	232	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	232	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
231	0	EP	call site: 00000	LZ4_compress_HC

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

55

Reachable functions

55

Percentage of reachable functions covered

0.0%

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
ossfuzz/round_trip_hc_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	6
lib/lz4.c	6
lib/lz4hc.c	32
lib/./lz4.c	8

Fuzzer: compress_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	62	51.2%
gold	[1:9]	2	1.65%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	57	47.1%
All colors	121	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
31	47	LZ4_NbCommonBytes	call site: 00047	LZ4_NbCommonBytes
20	21	LZ4_compress_fast_extState	call site: 00021	LZ4_writeLE16
6	89	LZ4_readLE16	call site: 00089	__assert_fail
2	43	LZ4_writeLE16	call site: 00043	LZ4_NbCommonBytes
2	81	LZ4_compress_fast_extState	call site: 00081	LZ4_largeInputTableType
1	85	LZ4_decompress_safe	call site: 00085	__assert_fail

Runtime coverage analysis

Covered functions

41

Functions that are reachable but not covered

5

Reachable functions

32

Percentage of reachable functions covered

84.38%

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
ossfuzz/compress_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4.c	22

Fuzzer: decompress_frame_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	24	13.4%
gold	[1:9]	1	0.56%
yellow	[10:29]	1	0.56%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	152	85.3%
All colors	178	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	114	LZ4_XXH32	call site: 00114	XXH_read32
6	131	LZ4_readLE16	call site: 00131	__assert_fail
2	59	LZ4_XXH32_update	call site: 00059	XXH_read32
2	62	LZ4_XXH32_update	call site: 00062	XXH_memcpy
2	111	LZ4_XXH32	call site: 00111	XXH_read32
2	121	LZ4_XXH32	call site: 00121	XXH32_finalize
1	17	LZ4F_calloc	call site: 00017	LZ4F_returnErrorCode
1	40	LZ4F_decodeHeader	call site: 00040	LZ4F_returnErrorCode
1	105	XXH32_finalize	call site: 00105	XXH32_finalize
1	127	LZ4_decompress_safe	call site: 00127	__assert_fail

Runtime coverage analysis

Covered functions

54

Functions that are reachable but not covered

5

Reachable functions

48

Percentage of reachable functions covered

89.58%

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
ossfuzz/decompress_frame_fuzzer.c	2
ossfuzz/fuzz_data_producer.c	6
lib/lz4frame.c	16
lib/xxhash.c	11
lib/lz4.c	9

Fuzzer: round_trip_frame_uncompressed_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	357	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	357	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
356	0	EP	call site: 00000	compress_independent_block_mode

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

103

Reachable functions

103

Percentage of reachable functions covered

0.0%

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
ossfuzz/round_trip_frame_uncompressed_fuzzer.c	4
ossfuzz/fuzz_data_producer.c	8
lib/lz4.c	21
lib/lz4frame.c	35
lib/lz4hc.c	19
lib/./lz4.c	3
lib/xxhash.c	11

Fuzzer: compress_hc_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	110	44.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	136	55.2%
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
31	142	LZ4HC_reverseCountPattern	call site: 00142	LZ4HC_countPattern
22	111	LZ4HC_hashPtr	call site: 00111	LZ4HC_countPattern
17	178	LZ4HC_compress_optimal	call site: 00178	LZ4HC_countPattern
13	197	LZ4HC_compress_optimal	call site: 00197	LZ4HC_compress_generic
6	216	LZ4_readLE16	call site: 00216	__assert_fail
5	78	LZ4MID_compress	call site: 00078	LZ4_NbCommonBytes
5	136	LZ4HC_countPattern	call site: 00136	LZ4HC_countPattern
4	58	LZ4MID_compress	call site: 00058	LZ4_NbCommonBytes
3	107	LZ4HC_compress_generic_internal	call site: 00107	LZ4HC_hashPtr
1	22	LZ4_compress_HC_extStateHC_fastReset	call site: 00022	LZ4_initStreamHC
1	27	LZ4HC_init_internal	call site: 00027	LZ4HC_clearTables
1	38	LZ4MID_compress	call site: 00038	LZ4HC_getCLevelParams

Runtime coverage analysis

Covered functions

73

Functions that are reachable but not covered

10

Reachable functions

56

Percentage of reachable functions covered

82.14%

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
ossfuzz/compress_hc_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4hc.c	34
lib/./lz4.c	8
lib/lz4.c	6

Fuzzer: decompress_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	25	36.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	43	63.2%
All colors	68	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
9	24	LZ4_decompress_safe	call site: 00024	LZ4_decompress_safe_withPrefix64k
9	48	LZ4_decompress_safe_partial_usingDict	call site: 00048	LZ4_decompress_safe_partial_withPrefix64k
6	17	LZ4_readLE16	call site: 00017	__assert_fail
1	13	LZ4_decompress_safe	call site: 00013	__assert_fail

Runtime coverage analysis

Covered functions

22

Functions that are reachable but not covered

7

Reachable functions

23

Percentage of reachable functions covered

69.57%

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
ossfuzz/decompress_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4.c	14

Fuzzer: round_trip_stream_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	36	39.1%
gold	[1:9]	0	0.0%
yellow	[10:29]	1	1.08%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	55	59.7%
All colors	92	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
20	20	XXH32_finalize	call site: 00020	XXH_read32
6	6	LZ4_XXH32	call site: 00006	XXH_read32
4	13	LZ4_XXH32	call site: 00013	XXH_read32
2	3	LZ4_XXH32	call site: 00003	XXH_read32
2	42	XXH32_finalize	call site: 00042	XXH32_finalize
1	71	state_reset	call site: 00071	LZ4_initStreamHC
1	77	LZ4_resetStreamHC_fast	call site: 00077	LZ4_setStreamDecode

Runtime coverage analysis

Covered functions

130

Functions that are reachable but not covered

7

Reachable functions

38

Percentage of reachable functions covered

81.58%

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
ossfuzz/round_trip_stream_fuzzer.c	7
ossfuzz/./fuzz_helpers.h	3
lib/xxhash.c	7
lib/lz4.c	10
lib/lz4hc.c	6
lib/./lz4.c	1

Fuzzer: compress_frame_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	101	28.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	252	71.3%
All colors	353	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
21	68	LZ4F_compressBegin_internal	call site: 00068	LZ4_loadDictHC
14	171	LZ4F_makeBlock	call site: 00171	LZ4F_makeBlock
6	114	LZ4_XXH32	call site: 00114	XXH_read32
6	283	LZ4_readLE16	call site: 00283	__assert_fail
4	90	LZ4HC_init_internal	call site: 00090	LZ4MID_fillHTable
4	295	LZ4_decompress_safe_usingDict	call site: 00295	LZ4_decompress_safe_withSmallPrefix
3	49	LZ4F_compressBegin_internal	call site: 00049	LZ4_initStreamHC
3	53	LZ4F_compressBegin_internal	call site: 00053	LZ4F_free
3	58	LZ4F_compressBegin_internal	call site: 00058	LZ4_resetStream_fast
3	101	LZ4MID_hash8Ptr	call site: 00101	LZ4MID_hash8Ptr
3	190	LZ4F_compressUpdateImpl	call site: 00190	LZ4F_localSaveDict
3	266	LZ4F_updateDict	call site: 00266	__assert_fail

Runtime coverage analysis

Covered functions

146

Functions that are reachable but not covered

21

Reachable functions

101

Percentage of reachable functions covered

79.21%

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
ossfuzz/compress_frame_fuzzer.c	2
ossfuzz/fuzz_data_producer.c	8
lib/lz4frame.c	35
lib/lz4.c	20
lib/lz4hc.c	19
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	1

Fuzzer: compress_frame_stream_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

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	75	19.1%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	317	80.8%
All colors	392	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
21	134	LZ4F_compressBegin_internal	call site: 00134	LZ4_loadDictHC
6	6	LZ4_XXH32	call site: 00006	XXH_read32
6	331	LZ4_readLE16	call site: 00331	__assert_fail
4	156	LZ4HC_init_internal	call site: 00156	LZ4MID_fillHTable
3	115	LZ4F_compressBegin_internal	call site: 00115	LZ4_initStreamHC
3	124	LZ4F_compressBegin_internal	call site: 00124	LZ4_resetStream_fast
3	167	LZ4MID_hash8Ptr	call site: 00167	LZ4MID_hash8Ptr
3	257	checkInvalidated	call site: 00257	LZ4F_getErrorCode
3	314	LZ4F_updateDict	call site: 00314	__assert_fail
3	364	LZ4F_decompress	call site: 00364	LZ4F_readLE32
2	3	LZ4_XXH32	call site: 00003	XXH_read32
2	42	XXH32_finalize	call site: 00042	XXH32_finalize

Runtime coverage analysis

Covered functions

156

Functions that are reachable but not covered

17

Reachable functions

104

Percentage of reachable functions covered

83.65%

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
ossfuzz/compress_frame_stream_fuzzer.c	6
ossfuzz/./fuzz_helpers.h	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	3
lib/lz4frame.c	37
lib/lz4.c	20
lib/lz4hc.c	19
lib/./lz4.c	3

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
LZ4F_compressBlock	/src/lz4/lib/lz4frame.c	7	['N/A', 'N/A', 'N/A', 'int', 'int', 'int', 'N/A']	4	0	76	9	4	28	0	1833	1757
LZ4_compress_forceExtDict	/src/lz4/lib/lz4.c	4	['N/A', 'N/A', 'N/A', 'int']	2	0	8560	1120	281	12	0	311	281
state_loadDictHCRoundTrip	/src/lz4/ossfuzz/round_trip_stream_fuzzer.c	1	['N/A']	9	0	39	3	2	61	0	1596	142
LZ4_XXH64	/src/lz4/lib/xxhash.c	3	['N/A', 'size_t', 'size_t']	2	0	750	90	31	10	0	133	125
LZ4_XXH64_update	/src/lz4/lib/xxhash.c	3	['N/A', 'N/A', 'size_t']	1	0	1498	184	63	5	0	73	63
LZ4_decompress_fast_continue	/src/lz4/lib/lz4.c	4	['N/A', 'N/A', 'N/A', 'int']	3	0	517	59	19	7	0	58	49

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

Functions statically reachable by fuzzers

192 / 273

Cyclomatic complexity statically reachable by fuzzers

5790 / 6075

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

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.

ossfuzz/round_trip_frame_fuzzer.c

Dictionary

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

ossfuzz/round_trip_fuzzer.c

Dictionary

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

ossfuzz/round_trip_hc_fuzzer.c

Dictionary

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

ossfuzz/compress_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=['LZ4_NbCommonBytes', 'LZ4_compress_fast_extState', 'LZ4_readLE16', 'LZ4_writeLE16', 'LZ4_decompress_safe']

ossfuzz/decompress_frame_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=['LZ4_XXH32', 'LZ4_readLE16', 'LZ4_XXH32_update', 'LZ4F_calloc', 'LZ4F_decodeHeader', 'XXH32_finalize', 'LZ4_decompress_safe']

ossfuzz/round_trip_frame_uncompressed_fuzzer.c

Dictionary

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

ossfuzz/compress_hc_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=['LZ4HC_reverseCountPattern', 'LZ4HC_hashPtr', 'LZ4HC_compress_optimal', 'LZ4_readLE16', 'LZ4MID_compress', 'LZ4HC_countPattern', 'LZ4HC_compress_generic_internal', 'LZ4_compress_HC_extStateHC_fastReset']

ossfuzz/decompress_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=['LZ4_decompress_safe', 'LZ4_decompress_safe_partial_usingDict', 'LZ4_readLE16']

ossfuzz/round_trip_stream_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=['XXH32_finalize', 'LZ4_XXH32', 'state_reset', 'LZ4_resetStreamHC_fast']

ossfuzz/compress_frame_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=['LZ4F_compressBegin_internal', 'LZ4F_makeBlock', 'LZ4_XXH32', 'LZ4_readLE16', 'LZ4HC_init_internal', 'LZ4_decompress_safe_usingDict', 'LZ4MID_hash8Ptr']

ossfuzz/compress_frame_stream_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=['LZ4F_compressBegin_internal', 'LZ4_XXH32', 'LZ4_readLE16', 'LZ4HC_init_internal', 'LZ4MID_hash8Ptr', 'checkInvalidated', 'LZ4F_updateDict', 'LZ4F_decompress']

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

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/lz4/lib/lz4hc.c	['round_trip_frame_fuzzer', 'round_trip_hc_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['compress_hc_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/compress_hc_fuzzer.c	['compress_hc_fuzzer']	['compress_hc_fuzzer']
/src/lz4/ossfuzz/decompress_frame_fuzzer.c	['decompress_frame_fuzzer']	['decompress_frame_fuzzer']
/src/lz4/ossfuzz/decompress_fuzzer.c	['decompress_fuzzer']	['decompress_fuzzer']
/src/lz4/ossfuzz/round_trip_frame_uncompressed_fuzzer.c	['round_trip_frame_uncompressed_fuzzer']	[]
/src/lz4/lib/xxhash.c	['round_trip_frame_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['decompress_frame_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/lib/lz4.c	['round_trip_frame_fuzzer', 'round_trip_fuzzer', 'round_trip_hc_fuzzer', 'compress_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'decompress_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['compress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'decompress_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/round_trip_frame_fuzzer.c	['round_trip_frame_fuzzer']	[]
/src/lz4/ossfuzz/round_trip_stream_fuzzer.c	['round_trip_stream_fuzzer']	['round_trip_stream_fuzzer']
/src/lz4/ossfuzz/round_trip_hc_fuzzer.c	['round_trip_hc_fuzzer']	[]
/src/lz4/ossfuzz/lz4_helpers.c	['round_trip_frame_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/compress_fuzzer.c	['compress_fuzzer']	['compress_fuzzer']
/src/lz4/ossfuzz/compress_frame_stream_fuzzer.c	['compress_frame_stream_fuzzer']	['compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/fuzz_data_producer.c	['round_trip_frame_fuzzer', 'round_trip_fuzzer', 'round_trip_hc_fuzzer', 'compress_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'decompress_fuzzer', 'compress_frame_fuzzer']	['compress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'decompress_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/compress_frame_fuzzer.c	['compress_frame_fuzzer']	['compress_frame_fuzzer']
/src/lz4/ossfuzz/round_trip_fuzzer.c	['round_trip_fuzzer']	[]
/src/lz4/lib/lz4frame.c	['round_trip_frame_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['decompress_frame_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/lib/./lz4.c	['round_trip_frame_fuzzer', 'round_trip_hc_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']	['compress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'decompress_fuzzer', 'round_trip_stream_fuzzer', 'compress_frame_fuzzer', 'compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/./fuzz_helpers.h	['round_trip_stream_fuzzer', 'compress_frame_stream_fuzzer']	[]

Directories in report

Directory
/src/lz4/lib/
/src/lz4/lib/./
/src/lz4/ossfuzz/./
/src/lz4/ossfuzz/