High level conclusions

Fuzzers reach 63.21% code coverage.

Fuzzers reach 56.73% of cyclomatic complexity.

Fuzzers reach 58.23% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

152 / 261

Cyclomatic complexity statically reachable by fuzzers

3540 / 6239

Runtime code coverage of functions

165 / 261

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: 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: 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	53.4%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	54	46.5%
All colors	116	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
32	46	LZ4_NbCommonBytes	call site: 00046	LZ4_NbCommonBytes
20	20	LZ4_compress_fast_extState	call site: 00020	LZ4_writeLE16
6	86	LZ4_readLE16	call site: 00086	__assert_fail
2	42	LZ4_writeLE16	call site: 00042	LZ4_NbCommonBytes
1	79	LZ4_compress_fast_extState	call site: 00079	__assert_fail
1	82	LZ4_decompress_safe	call site: 00082	__assert_fail

Runtime coverage analysis

Covered functions

39

Functions that are reachable but not covered

5

Reachable functions

30

Percentage of reachable functions covered

83.33%

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	20

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	33	18.9%
gold	[1:9]	0	0.0%
yellow	[10:29]	2	1.14%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	139	79.8%
All colors	174	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	110	LZ4_XXH32	call site: 00110	XXH_read32
6	127	LZ4_readLE16	call site: 00127	__assert_fail
4	117	LZ4_XXH32	call site: 00117	LZ4_decompress_safe_usingDict
4	134	LZ4_decompress_safe	call site: 00134	LZ4_decompress_safe_withPrefix64k
3	148	LZ4_decompress_safe_forceExtDict	call site: 00148	LZ4_XXH32_update
2	55	LZ4_XXH32_update	call site: 00055	XXH_read32
2	58	LZ4_XXH32_update	call site: 00058	XXH_memcpy
2	107	LZ4_XXH32	call site: 00107	XXH_read32
1	14	LZ4F_calloc	call site: 00014	LZ4F_returnErrorCode
1	36	LZ4F_decodeHeader	call site: 00036	LZ4F_returnErrorCode
1	101	XXH32_finalize	call site: 00101	XXH32_finalize
1	123	LZ4_decompress_safe	call site: 00123	__assert_fail

Runtime coverage analysis

Covered functions

52

Functions that are reachable but not covered

6

Reachable functions

47

Percentage of reachable functions covered

87.23%

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	5
lib/lz4frame.c	16
lib/xxhash.c	11
lib/lz4.c	9

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	71	39.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	111	60.9%
All colors	182	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	48	LZ4_NbCommonBytes	call site: 00048	LZ4_NbCommonBytes
20	22	LZ4_compress_fast_extState	call site: 00022	LZ4_writeLE16
9	119	LZ4_decompress_safe_partial_usingDict	call site: 00119	LZ4_decompress_safe_partial_withPrefix64k
6	90	LZ4_readLE16	call site: 00090	__assert_fail
2	44	LZ4_writeLE16	call site: 00044	LZ4_NbCommonBytes
2	80	LZ4_compress_fast_extState	call site: 00080	__assert_fail
1	86	LZ4_decompress_safe	call site: 00086	__assert_fail

Runtime coverage analysis

Covered functions

40

Functions that are reachable but not covered

7

Reachable functions

33

Percentage of reachable functions covered

78.79%

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_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4.c	23

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	109	43.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	140	56.2%
All colors	249	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
34	138	LZ4HC_reverseCountPattern	call site: 00138	LZ4HC_countPattern
22	109	LZ4HC_hashPtr	call site: 00109	LZ4HC_countPattern
15	211	LZ4HC_compress_optimal	call site: 00211	LZ4HC_compress_generic_dictCtx
8	178	LZ4HC_compress_optimal	call site: 00178	LZ4HC_countPattern
6	235	LZ4_readLE16	call site: 00235	__assert_fail
5	78	LZ4MID_compress	call site: 00078	LZ4_NbCommonBytes
4	58	LZ4MID_compress	call site: 00058	LZ4_NbCommonBytes
3	101	LZ4MID_compress	call site: 00101	LZ4_writeLE16
3	105	LZ4HC_compress_generic_internal	call site: 00105	LZ4HC_hashPtr
3	134	LZ4HC_countPattern	call site: 00134	LZ4HC_reverseCountPattern
1	22	LZ4_compress_HC_extStateHC_fastReset	call site: 00022	LZ4_initStreamHC
1	27	LZ4HC_init_internal	call site: 00027	LZ4HC_clearTables

Runtime coverage analysis

Covered functions

61

Functions that are reachable but not covered

10

Reachable functions

53

Percentage of reachable functions covered

81.13%

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_hc_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	6
lib/lz4.c	6
lib/lz4hc.c	30
lib/./lz4.c	8

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	103	39.1%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	160	60.8%
All colors	263	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
34	138	LZ4HC_reverseCountPattern	call site: 00138	LZ4HC_countPattern
22	109	LZ4HC_hashPtr	call site: 00109	LZ4HC_countPattern
13	214	LZ4HC_compress_optimal	call site: 00214	LZ4HC_compress_generic
8	178	LZ4HC_compress_optimal	call site: 00178	LZ4HC_countPattern
6	233	LZ4_readLE16	call site: 00233	__assert_fail
5	78	LZ4MID_compress	call site: 00078	LZ4_NbCommonBytes
4	58	LZ4MID_compress	call site: 00058	LZ4_NbCommonBytes
3	105	LZ4HC_compress_generic_internal	call site: 00105	LZ4HC_hashPtr
3	134	LZ4HC_countPattern	call site: 00134	LZ4HC_reverseCountPattern
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

62

Functions that are reachable but not covered

10

Reachable functions

54

Percentage of reachable functions covered

81.48%

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.

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	32
lib/./lz4.c	8
lib/lz4.c	6

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]	1	1.08%
yellow	[10:29]	0	0.0%
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

118

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: 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	100	30.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	2	0.60%
lawngreen	50+	231	69.3%
All colors	333	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
11	172	LZ4F_makeBlock	call site: 00172	LZ4F_makeBlock
7	160	LZ4F_compressUpdateImpl	call site: 00160	LZ4F_flush
6	114	LZ4_XXH32	call site: 00114	XXH_read32
6	279	LZ4_readLE16	call site: 00279	__assert_fail
4	90	LZ4HC_init_internal	call site: 00090	LZ4MID_fillHTable
4	291	LZ4_decompress_safe_usingDict	call site: 00291	LZ4_decompress_safe_withSmallPrefix
3	50	LZ4F_compressBegin_internal	call site: 00050	LZ4_initStreamHC
3	54	LZ4F_compressBegin_internal	call site: 00054	LZ4F_free
3	101	LZ4MID_hash8Ptr	call site: 00101	LZ4MID_hash8Ptr
3	186	LZ4F_compressUpdateImpl	call site: 00186	LZ4F_localSaveDict
3	262	LZ4F_updateDict	call site: 00262	__assert_fail

Runtime coverage analysis

Covered functions

133

Functions that are reachable but not covered

21

Reachable functions

102

Percentage of reachable functions covered

79.41%

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_frame_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	8
lib/lz4.c	22
lib/lz4frame.c	34
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.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	126	38.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	2	0.60%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	203	61.3%
All colors	331	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
17	284	LZ4_decompress_safe	call site: 00284	LZ4_decompress_safe_withPrefix64k
12	172	LZ4F_makeBlock	call site: 00172	LZ4F_makeBlock
7	160	LZ4F_compressUpdateImpl	call site: 00160	LZ4F_flush
7	256	LZ4F_decompress	call site: 00256	LZ4F_updateDict
6	114	LZ4_XXH32	call site: 00114	XXH_read32
6	277	LZ4_readLE16	call site: 00277	__assert_fail
4	58	LZ4F_compressBegin_internal	call site: 00058	LZ4F_initStream
4	90	LZ4HC_init_internal	call site: 00090	LZ4MID_fillHTable
4	185	LZ4F_compressUpdateImpl	call site: 00185	LZ4F_localSaveDict
3	50	LZ4F_compressBegin_internal	call site: 00050	LZ4_initStreamHC
3	54	LZ4F_compressBegin_internal	call site: 00054	LZ4F_free

Runtime coverage analysis

Covered functions

123

Functions that are reachable but not covered

24

Reachable functions

101

Percentage of reachable functions covered

76.24%

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	1
ossfuzz/fuzz_data_producer.c	8
lib/lz4frame.c	34
lib/lz4.c	21
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	1

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	109	30.9%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	2	0.56%
lawngreen	50+	241	68.4%
All colors	352	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	80	LZ4F_compressBegin_internal	call site: 00080	LZ4_loadDictHC
14	305	LZ4_decompress_safe	call site: 00305	LZ4_decompress_safe_withPrefix64k
10	186	LZ4F_flush	call site: 00186	LZ4F_makeBlock
7	277	LZ4F_decompress	call site: 00277	LZ4F_updateDict
6	126	LZ4_XXH32	call site: 00126	XXH_read32
6	298	LZ4_readLE16	call site: 00298	__assert_fail
4	70	LZ4F_compressBegin_internal	call site: 00070	LZ4F_initStream
4	102	LZ4HC_init_internal	call site: 00102	LZ4MID_fillHTable
4	198	LZ4F_compressUpdateImpl	call site: 00198	LZ4F_localSaveDict
3	62	LZ4F_compressBegin_internal	call site: 00062	LZ4_initStreamHC
3	113	LZ4MID_hash8Ptr	call site: 00113	LZ4MID_hash8Ptr
3	331	LZ4F_decompress	call site: 00331	LZ4F_readLE32

Runtime coverage analysis

Covered functions

127

Functions that are reachable but not covered

25

Reachable functions

105

Percentage of reachable functions covered

76.19%

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_frame_uncompressed_fuzzer.c	4
ossfuzz/fuzz_data_producer.c	8
lib/lz4.c	22
lib/lz4frame.c	35
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11

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	23	0	1812	1747
LZ4_compress_forceExtDict	/src/lz4/lib/lz4.c	4	['N/A', 'N/A', 'N/A', 'int']	2	0	8578	1123	282	11	0	310	282
state_loadDictHCRoundTrip	/src/lz4/ossfuzz/round_trip_stream_fuzzer.c	1	['N/A']	9	0	39	3	2	59	0	1799	150
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

178 / 261

Cyclomatic complexity statically reachable by fuzzers

5956 / 6239

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/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/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_decompress_safe', 'LZ4_decompress_safe_forceExtDict', 'LZ4_XXH32_update', 'LZ4F_calloc', 'LZ4F_decodeHeader']

ossfuzz/round_trip_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_decompress_safe_partial_usingDict', 'LZ4_readLE16', 'LZ4_writeLE16', 'LZ4_decompress_safe']

ossfuzz/round_trip_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_compress_generic_internal', 'LZ4HC_countPattern']

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_compress_generic_internal', 'LZ4HC_countPattern', 'LZ4_compress_HC_extStateHC_fastReset']

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/round_trip_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', 'LZ4F_compressUpdateImpl', 'LZ4_XXH32', 'LZ4_readLE16', 'LZ4HC_init_internal', 'LZ4_decompress_safe_usingDict', 'LZ4MID_hash8Ptr']

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', 'LZ4_decompress_safe', 'LZ4F_makeBlock', 'LZ4F_compressUpdateImpl', 'LZ4F_decompress', 'LZ4_XXH32', 'LZ4_readLE16', 'LZ4HC_init_internal']

ossfuzz/round_trip_frame_uncompressed_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_decompress_safe', 'LZ4F_flush', 'LZ4F_decompress', 'LZ4_XXH32', 'LZ4_readLE16', 'LZ4HC_init_internal', 'LZ4F_compressUpdateImpl']

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

Directories in report

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