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_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	34	19.5%
gold	[1:9]	1	0.57%
yellow	[10:29]	1	0.57%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	138	79.3%
All colors	174	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
124	124	1 : View List ['LZ4_decompress_safe_withPrefix64k']	124	124	LZ4_decompress_safe_usingDict	call site: 00122	/src/lz4/lib/lz4.c:2726
0	2	1 : View List ['LZ4F_returnErrorCode']	0	2	LZ4F_getBlockSize	call site: 00036	/src/lz4/lib/lz4frame.c:338
0	2	1 : View List ['LZ4F_returnErrorCode']	0	2	LZ4F_createDecompressionContext	call site: 00012	/src/lz4/lib/lz4frame.c:1323
0	0	None	32	86	LZ4_XXH32_update	call site: 00057	/src/lz4/lib/xxhash.c:519
0	0	None	16	84	LZ4_XXH32	call site: 00116	/src/lz4/lib/xxhash.c:411
0	0	None	0	1585	LZ4F_decompress	call site: 00049	/src/lz4/lib/lz4frame.c:1749
0	0	None	0	1585	LZ4F_decompress	call site: 00052	/src/lz4/lib/lz4frame.c:1792
0	0	None	0	1585	LZ4F_decompress	call site: 00062	/src/lz4/lib/lz4frame.c:1844
0	0	None	0	1585	LZ4F_decompress	call site: 00062	/src/lz4/lib/lz4frame.c:1850
0	0	None	0	1585	LZ4F_decompress	call site: 00070	/src/lz4/lib/lz4frame.c:1887
0	0	None	0	1585	LZ4F_decompress	call site: 00106	/src/lz4/lib/lz4frame.c:1915
0	0	None	0	1585	LZ4F_decompress	call site: 00151	/src/lz4/lib/lz4frame.c:1956

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: 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 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
1142	1142	1 : View List ['LZ4HC_compress_generic_dictCtx']	1142	1142	LZ4HC_compress_generic	call site: 00030	/src/lz4/lib/lz4hc.c:1527
0	12	1 : View List ['LZ4_initStreamHC']	0	15	LZ4_resetStreamHC_fast	call site: 00022	/src/lz4/lib/lz4hc.c:1648
0	0	None	12	753	LZ4HC_compress_optimal	call site: 00197	/src/lz4/lib/lz4hc.c:2025
0	0	None	0	1145	LZ4_compress_HC_extStateHC_fastReset	call site: 00029	/src/lz4/lib/lz4hc.c:1555
0	0	None	0	265	LZ4MID_compress	call site: 00051	/src/lz4/lib/lz4hc.c:610
0	0	None	0	265	LZ4MID_compress	call site: 00067	/src/lz4/lib/lz4hc.c:641
0	0	None	0	265	LZ4MID_compress	call site: 00082	/src/lz4/lib/lz4hc.c:682
0	0	None	0	0	LZ4_readLE16	call site: 00232	/src/lz4/lib/lz4.c:432
0	0	None	0	0	LZ4_NbCommonBytes	call site: 00056	/src/lz4/lib/lz4.c:584
0	0	None	0	0	LZ4_writeLE16	call site: 00089	/src/lz4/lib/lz4.c:454
0	0	None	0	0	LZ4_readLE64	call site: 00047	/src/lz4/lib/lz4hc.c:155
0	0	None	0	0	LZ4HC_countPattern	call site: 00134	/src/lz4/lib/lz4hc.c:864

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: 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	130	39.2%
gold	[1:9]	0	0.0%
yellow	[10:29]	2	0.60%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	199	60.1%
All colors	331	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
1190	1190	1 : View List ['LZ4_compress_HC_continue']	1190	1190	LZ4F_compressBlockHC	call site: 00000	/src/lz4/lib/lz4frame.c:950
1142	1142	1 : View List ['LZ4HC_compress_generic_dictCtx']	1142	1142	LZ4HC_compress_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1527
882	882	1 : View List ['LZ4_compress_fast_continue']	882	882	LZ4F_compressBlock	call site: 00000	/src/lz4/lib/lz4frame.c:932
372	372	3 : View List ['LZ4_decompress_safe_withPrefix64k', 'LZ4_decompress_safe_forceExtDict', 'LZ4_decompress_safe_withSmallPrefix']	372	372	LZ4_decompress_safe_usingDict	call site: 00271	/src/lz4/lib/lz4.c:2723
77	79	3 : View List ['LZ4F_returnErrorCode', 'LZ4_loadDictHC', 'LZ4_loadDict']	79	166	LZ4F_compressBegin_internal	call site: 00068	/src/lz4/lib/lz4frame.c:781
20	116	4 : View List ['LZ4F_localSaveDict', 'LZ4F_selectCompression', 'LZ4F_makeBlock', 'LZ4F_returnErrorCode']	20	116	LZ4F_flush	call site: 00163	/src/lz4/lib/lz4frame.c:1183
20	20	1 : View List ['LZ4F_localSaveDict']	20	93	LZ4F_compressUpdateImpl	call site: 00187	/src/lz4/lib/lz4frame.c:1097
19	19	2 : View List ['LZ4_attach_dictionary', 'LZ4_resetStream_fast']	19	19	LZ4F_initStream	call site: 00059	/src/lz4/lib/lz4frame.c:660
2	2	1 : View List ['LZ4F_writeLE64']	2	85	LZ4F_compressBegin_internal	call site: 00106	/src/lz4/lib/lz4frame.c:811
2	2	1 : View List ['LZ4F_readLE64']	2	4	LZ4F_decodeHeader	call site: 00239	/src/lz4/lib/lz4frame.c:1453
0	119	1 : View List ['LZ4F_flush']	40	493	LZ4F_compressUpdateImpl	call site: 00162	/src/lz4/lib/lz4frame.c:1030
0	43	1 : View List ['LZ4F_initStream']	79	211	LZ4F_compressBegin_internal	call site: 00058	/src/lz4/lib/lz4frame.c:774

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_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 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
1142	1142	1 : View List ['LZ4HC_compress_generic_dictCtx']	1142	1142	LZ4HC_compress_generic	call site: 00030	/src/lz4/lib/lz4hc.c:1527
0	12	1 : View List ['LZ4_initStreamHC']	0	15	LZ4_resetStreamHC_fast	call site: 00022	/src/lz4/lib/lz4hc.c:1648
0	0	None	12	753	LZ4HC_compress_optimal	call site: 00197	/src/lz4/lib/lz4hc.c:2025
0	0	None	0	1145	LZ4_compress_HC_extStateHC_fastReset	call site: 00029	/src/lz4/lib/lz4hc.c:1555
0	0	None	0	265	LZ4MID_compress	call site: 00051	/src/lz4/lib/lz4hc.c:610
0	0	None	0	265	LZ4MID_compress	call site: 00067	/src/lz4/lib/lz4hc.c:641
0	0	None	0	265	LZ4MID_compress	call site: 00082	/src/lz4/lib/lz4hc.c:682
0	0	None	0	7	LZ4MID_compress	call site: 00088	/src/lz4/lib/lz4hc.c:714
0	0	None	0	7	LZ4HC_compress_optimal	call site: 00193	/src/lz4/lib/lz4hc.c:1939
0	0	None	0	0	LZ4_readLE16	call site: 00234	/src/lz4/lib/lz4.c:432
0	0	None	0	0	LZ4_NbCommonBytes	call site: 00056	/src/lz4/lib/lz4.c:584
0	0	None	0	0	LZ4_writeLE16	call site: 00089	/src/lz4/lib/lz4.c:454

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: 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 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
0	54	1 : View List ['LZ4_loadDictHC']	0	1214	LZ4_compressHC_continue_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1744
0	12	1 : View List ['LZ4_initStreamHC']	0	15	LZ4_resetStreamHC_fast	call site: 00071	/src/lz4/lib/lz4hc.c:1648
0	0	None	24	84	LZ4_XXH32	call site: 00012	/src/lz4/lib/xxhash.c:411
0	0	None	0	1185	LZ4_compress_HC_continue	call site: 00000	/src/lz4/lib/lz4hc.c:1774
0	0	None	0	753	LZ4HC_compress_optimal	call site: 00000	/src/lz4/lib/lz4hc.c:2025
0	0	None	0	7	LZ4MID_compress	call site: 00000	/src/lz4/lib/lz4hc.c:714
0	0	None	0	7	LZ4HC_compress_optimal	call site: 00000	/src/lz4/lib/lz4hc.c:1939
0	0	3 : View List ['LZ4_read32.445', 'LZ4_isLittleEndian.435', 'LZ4_read_ARCH.442']	0	0	LZ4_loadDict_internal	call site: 00000	/src/lz4/lib/lz4.c:1632
0	0	None	0	0	LZ4_attach_dictionary	call site: 00000	/src/lz4/lib/lz4.c:1675
0	0	None	0	0	LZ4_writeLE16	call site: 00000	/src/lz4/lib/lz4.c:454
0	0	None	0	0	LZ4_NbCommonBytes	call site: 00000	/src/lz4/lib/lz4.c:584
0	0	None	0	0	LZ4_readLE16	call site: 00000	/src/lz4/lib/lz4.c:432

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_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 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
250	250	2 : View List ['LZ4_decompress_safe_partial_withSmallPrefix', 'LZ4_decompress_safe_partial_withPrefix64k']	250	250	LZ4_decompress_safe_partial_usingDict	call site: 00119	/src/lz4/lib/lz4.c:2740
0	0	None	16	24	LZ4_compress_fast_extState	call site: 00079	/src/lz4/lib/lz4.c:1390
0	0	None	0	0	LZ4_writeLE16	call site: 00043	/src/lz4/lib/lz4.c:454
0	0	None	0	0	LZ4_NbCommonBytes	call site: 00048	/src/lz4/lib/lz4.c:584
0	0	None	0	0	LZ4_readLE16	call site: 00089	/src/lz4/lib/lz4.c:432
0	0	None	0	0	FUZZ_dataProducer_retrieve32	call site: 00004	/src/lz4/ossfuzz/fuzz_data_producer.c:23
0	0	None	0	0	FUZZ_getRange_from_uint32	call site: 00006	/src/lz4/ossfuzz/fuzz_data_producer.c:37

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: 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 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
250	250	2 : View List ['LZ4_decompress_safe_partial_withSmallPrefix', 'LZ4_decompress_safe_partial_withPrefix64k']	250	250	LZ4_decompress_safe_partial_usingDict	call site: 00048	/src/lz4/lib/lz4.c:2740
248	248	2 : View List ['LZ4_decompress_safe_withPrefix64k', 'LZ4_decompress_safe_withSmallPrefix']	248	248	LZ4_decompress_safe_usingDict	call site: 00012	/src/lz4/lib/lz4.c:2725
0	0	None	0	0	LZ4_readLE16	call site: 00016	/src/lz4/lib/lz4.c:432
0	0	None	0	0	FUZZ_dataProducer_retrieve32	call site: 00004	/src/lz4/ossfuzz/fuzz_data_producer.c:23
0	0	None	0	0	FUZZ_getRange_from_uint32	call site: 00006	/src/lz4/ossfuzz/fuzz_data_producer.c:37

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_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	106	31.8%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	2	0.60%
lawngreen	50+	225	67.5%
All colors	333	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
1142	1142	1 : View List ['LZ4HC_compress_generic_dictCtx']	1142	1142	LZ4HC_compress_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1527
124	124	1 : View List ['LZ4_decompress_safe_withSmallPrefix']	124	124	LZ4_decompress_safe_usingDict	call site: 00274	/src/lz4/lib/lz4.c:2726
79	79	3 : View List ['LZ4F_returnErrorCode', 'LZ4_loadDictHC', 'LZ4_loadDict']	81	166	LZ4F_compressBegin_internal	call site: 00068	/src/lz4/lib/lz4frame.c:781
54	54	1 : View List ['LZ4_loadDictHC']	69	1214	LZ4_compressHC_continue_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1744
24	116	4 : View List ['LZ4F_localSaveDict', 'LZ4F_selectCompression', 'LZ4F_makeBlock', 'LZ4F_returnErrorCode']	24	116	LZ4F_flush	call site: 00163	/src/lz4/lib/lz4frame.c:1183
20	20	1 : View List ['LZ4F_localSaveDict']	20	93	LZ4F_compressUpdateImpl	call site: 00187	/src/lz4/lib/lz4frame.c:1097
15	15	1 : View List ['LZ4HC_setExternalDict']	15	1160	LZ4_compressHC_continue_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1751
5	5	1 : View List ['LZ4_attach_dictionary']	5	5	LZ4F_initStream	call site: 00060	/src/lz4/lib/lz4frame.c:668
2	2	1 : View List ['LZ4F_writeLE64']	2	85	LZ4F_compressBegin_internal	call site: 00106	/src/lz4/lib/lz4frame.c:811
2	2	1 : View List ['LZ4F_readLE64']	2	4	LZ4F_decodeHeader	call site: 00241	/src/lz4/lib/lz4frame.c:1453
2	2	1 : View List ['LZ4F_returnErrorCode']	2	2	LZ4F_getBlockSize	call site: 00019	/src/lz4/lib/lz4frame.c:338
2	2	1 : View List ['LZ4F_returnErrorCode']	2	2	LZ4F_compressEnd	call site: 00211	/src/lz4/lib/lz4frame.c:1251

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_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	61	52.5%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	55	47.4%
All colors	116	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
0	0	None	8	12	LZ4_compress_fast_extState	call site: 00077	/src/lz4/lib/lz4.c:1391
0	0	None	0	0	LZ4_writeLE16	call site: 00041	/src/lz4/lib/lz4.c:454
0	0	None	0	0	LZ4_NbCommonBytes	call site: 00046	/src/lz4/lib/lz4.c:584
0	0	None	0	0	LZ4_readLE16	call site: 00085	/src/lz4/lib/lz4.c:432
0	0	None	0	0	FUZZ_dataProducer_retrieve32	call site: 00004	/src/lz4/ossfuzz/fuzz_data_producer.c:23
0	0	None	0	0	FUZZ_getRange_from_uint32	call site: 00007	/src/lz4/ossfuzz/fuzz_data_producer.c:37

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: 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	110	31.2%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	2	0.56%
lawngreen	50+	240	68.1%
All colors	352	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
1190	1190	1 : View List ['LZ4_compress_HC_continue']	1190	1190	LZ4F_compressBlockHC	call site: 00000	/src/lz4/lib/lz4frame.c:950
1142	1142	1 : View List ['LZ4HC_compress_generic_dictCtx']	1142	1142	LZ4HC_compress_generic	call site: 00000	/src/lz4/lib/lz4hc.c:1527
882	882	1 : View List ['LZ4_compress_fast_continue']	882	882	LZ4F_compressBlock	call site: 00000	/src/lz4/lib/lz4frame.c:932
372	372	3 : View List ['LZ4_decompress_safe_withPrefix64k', 'LZ4_decompress_safe_forceExtDict', 'LZ4_decompress_safe_withSmallPrefix']	372	372	LZ4_decompress_safe_usingDict	call site: 00292	/src/lz4/lib/lz4.c:2723
79	79	3 : View List ['LZ4F_returnErrorCode', 'LZ4_loadDictHC', 'LZ4_loadDict']	81	166	LZ4F_compressBegin_internal	call site: 00080	/src/lz4/lib/lz4frame.c:781
20	20	1 : View List ['LZ4F_localSaveDict']	20	20	LZ4F_flush	call site: 00186	/src/lz4/lib/lz4frame.c:1204
19	19	2 : View List ['LZ4_attach_dictionary', 'LZ4_resetStream_fast']	19	19	LZ4F_initStream	call site: 00071	/src/lz4/lib/lz4frame.c:660
2	2	1 : View List ['LZ4F_writeLE64']	2	85	LZ4F_compressBegin_internal	call site: 00118	/src/lz4/lib/lz4frame.c:811
2	2	1 : View List ['LZ4F_readLE64']	2	4	LZ4F_decodeHeader	call site: 00260	/src/lz4/lib/lz4frame.c:1453
2	2	1 : View List ['LZ4F_returnErrorCode']	2	2	LZ4F_getBlockSize	call site: 00029	/src/lz4/lib/lz4frame.c:338
2	2	1 : View List ['LZ4F_returnErrorCode']	2	2	LZ4F_compressEnd	call site: 00234	/src/lz4/lib/lz4frame.c:1251
2	2	1 : View List ['LZ4F_returnErrorCode']	2	2	LZ4F_createDecompressionContext	call site: 00242	/src/lz4/lib/lz4frame.c:1323

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	84	9	4	23	0	1812	1747
LZ4_compress_forceExtDict	/src/lz4/lib/lz4.c	4	['N/A', 'N/A', 'N/A', 'int']	2	0	9116	1123	282	11	0	310	282
state_loadDictHCRoundTrip	/src/lz4/ossfuzz/round_trip_stream_fuzzer.c	1	['N/A']	9	0	42	3	2	59	0	1799	150
LZ4_XXH64	/src/lz4/lib/xxhash.c	3	['N/A', 'size_t', 'size_t']	2	0	804	90	31	10	0	133	125
LZ4_XXH64_update	/src/lz4/lib/xxhash.c	3	['N/A', 'N/A', 'size_t']	1	0	1604	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	542	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_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', 'XXH32_finalize', 'LZ4F_calloc']

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/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_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/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']

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/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_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', 'LZ4_decompress_safe_withPrefix64k', 'LZ4HC_init_internal', 'LZ4F_updateDict']

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

Directories in report

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