High level conclusions

Fuzzers reach 73.22% code coverage.

Fuzzers reach 64.64% of cyclomatic complexity.

Fuzzers reach 70.49% of all functions.

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.

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_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.

Reachability and coverage overview

Functions statically reachable by fuzzers

258 / 366

Cyclomatic complexity statically reachable by fuzzers

6234 / 9643

Runtime code coverage of functions

268 / 366

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_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	208	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	208	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
207	0	EP	call site: 00000	LZ4_compress_default

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

38

Reachable functions

38

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	28

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	563	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	563	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
562	0	EP	call site: 00000	compress_round_trip

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

159

Reachable functions

159

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	3
ossfuzz/fuzz_data_producer.c	8
lib/lz4.c	22
lib/lz4frame.c	90
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11

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	29	40.2%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	43	59.7%
All colors	72	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
11	26	LZ4_decompress_safe	call site: 00026	LZ4_decompress_safe_withPrefix64k
9	52	LZ4_decompress_safe_partial_usingDict	call site: 00052	LZ4_decompress_safe_partial_withPrefix64k
8	17	LZ4_readLE16	call site: 00017	LZ4_copyMatchExact
1	13	LZ4_decompress_safe	call site: 00013	__assert_fail

Runtime coverage analysis

Covered functions

26

Functions that are reachable but not covered

7

Reachable functions

24

Percentage of reachable functions covered

70.83%

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_fuzzer.c	1
ossfuzz/fuzz_data_producer.c	5
lib/lz4.c	15

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	30	15.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	3	1.50%
greenyellow	[30:49]	3	1.50%
lawngreen	50+	163	81.9%
All colors	199	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
8	143	LZ4_readLE16	call site: 00143	LZ4_copyMatchExact
6	125	LZ4_XXH32	call site: 00125	XXH_read32
2	65	LZ4_XXH32_update	call site: 00065	XXH_read32
2	68	LZ4_XXH32_update	call site: 00068	XXH_memcpy
2	122	LZ4_XXH32	call site: 00122	XXH_read32
2	132	LZ4_XXH32	call site: 00132	XXH32_finalize
2	152	LZ4_decompress_safe	call site: 00152	__assert_fail
1	17	LZ4F_calloc	call site: 00017	LZ4F_returnErrorCode
1	44	LZ4F_decodeHeader	call site: 00044	LZ4F_returnErrorCode
1	53	LZ4F_decompress	call site: 00053	LZ4F_returnErrorCode
1	56	LZ4F_decompress	call site: 00056	LZ4F_returnErrorCode
1	116	XXH32_finalize	call site: 00116	XXH32_finalize

Runtime coverage analysis

Covered functions

62

Functions that are reachable but not covered

5

Reachable functions

53

Percentage of reachable functions covered

90.57%

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.

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	20
lib/xxhash.c	11
lib/lz4.c	10

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	45.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	131	54.3%
All colors	241	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
27	132	LZ4HC_reverseCountPattern	call site: 00132	LZ4HC_countPattern
25	98	LZ4HC_compress_generic_internal	call site: 00098	LZ4HC_countPattern
17	164	LZ4HC_compress_optimal	call site: 00164	LZ4HC_countPattern
14	187	LZ4HC_compress_generic_internal	call site: 00187	LZ4HC_compress_generic
8	207	LZ4_readLE16	call site: 00207	LZ4_copyMatchExact
5	126	LZ4HC_countPattern	call site: 00126	LZ4HC_countPattern
4	56	LZ4MID_compress	call site: 00056	LZ4_NbCommonBytes
2	49	LZ4MID_compress	call site: 00049	LZ4_NbCommonBytes
2	53	LZ4_NbCommonBytes	call site: 00053	LZ4_read32
2	216	LZ4_decompress_safe	call site: 00216	__assert_fail
1	25	LZ4HC_init_internal	call site: 00025	LZ4HC_clearTables
1	36	LZ4MID_compress	call site: 00036	LZ4HC_getCLevelParams

Runtime coverage analysis

Covered functions

75

Functions that are reachable but not covered

10

Reachable functions

57

Percentage of reachable functions covered

82.46%

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	7

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	85	58.2%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	61	41.7%
All colors	146	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
47	50	LZ4_NbCommonBytes	call site: 00050	LZ4_compress_resumeWithPrefix
22	22	LZ4_compress_fast_extState_fastReset	call site: 00022	LZ4_writeLE16
8	108	LZ4_readLE16	call site: 00108	LZ4_copyMatchExact
3	98	LZ4_compress_fast_extState_fastReset	call site: 00098	LZ4_compress_resumeWithPrefix
2	46	LZ4_writeLE16	call site: 00046	LZ4_NbCommonBytes
2	117	LZ4_decompress_safe	call site: 00117	__assert_fail
1	104	LZ4_decompress_safe	call site: 00104	__assert_fail

Runtime coverage analysis

Covered functions

48

Functions that are reachable but not covered

6

Reachable functions

35

Percentage of reachable functions covered

82.86%

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	25

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	551	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	551	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
550	0	EP	call site: 00000	FUZZ_decompressFrame

Runtime coverage analysis

Covered functions

0

Functions that are reachable but not covered

158

Reachable functions

158

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	22
lib/lz4frame.c	90
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	1

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	35	39.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	1	1.13%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	52	59.0%
All colors	88	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	73	LZ4_resetStreamHC_fast	call site: 00073	LZ4_setStreamDecode

Runtime coverage analysis

Covered functions

139

Functions that are reachable but not covered

7

Reachable functions

36

Percentage of reachable functions covered

80.56%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

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	4

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	121	53.3%
gold	[1:9]	0	0.0%
yellow	[10:29]	1	0.44%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	105	46.2%
All colors	227	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
27	132	LZ4HC_reverseCountPattern	call site: 00132	LZ4HC_countPattern
25	98	LZ4HC_compress_generic_internal	call site: 00098	LZ4HC_countPattern
17	164	LZ4HC_compress_optimal	call site: 00164	LZ4HC_countPattern
17	183	LZ4HC_compress_optimal	call site: 00183	LZ4HC_compress_generic_dictCtx
8	209	LZ4_readLE16	call site: 00209	LZ4_copyMatchExact
5	126	LZ4HC_countPattern	call site: 00126	LZ4HC_countPattern
4	56	LZ4MID_compress	call site: 00056	LZ4_NbCommonBytes
4	76	LZ4_writeLE16	call site: 00076	LZ4HC_encodeLastSequence_fillOutput
3	88	LZ4MID_compress	call site: 00088	LZ4MID_hash8Ptr
2	49	LZ4MID_compress	call site: 00049	LZ4_NbCommonBytes
2	53	LZ4_NbCommonBytes	call site: 00053	LZ4_read32
2	218	LZ4_decompress_safe	call site: 00218	__assert_fail

Runtime coverage analysis

Covered functions

73

Functions that are reachable but not covered

11

Reachable functions

56

Percentage of reachable functions covered

80.36%

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	7
lib/lz4hc.c	32
lib/./lz4.c	8

Fuzzer: file_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	266	36.9%
gold	[1:9]	1	0.13%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	1	0.13%
lawngreen	50+	452	62.7%
All colors	720	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
56	523	LZ4F_compressBlocks_internal	call site: 00523	LZ4F_mt_submitLast
30	460	LZ4F_headerChecksum	call site: 00460	LZ4F_mt_begin
26	326	LZ4F_freeCompressionContext	call site: 00326	LZ4F_mt_abort
25	391	LZ4F_initLZ4State	call site: 00391	LZ4F_digestRawDict
14	499	LZ4F_write	call site: 00499	LZ4F_mt_update
8	169	LZ4_readLE16	call site: 00169	LZ4_copyMatchExact
8	640	LZ4F_flushBlockPartial	call site: 00640	LZ4F_flushBlock
7	652	LZ4F_emitPending	call site: 00652	LZ4F_invalidateFrame
6	151	LZ4_XXH32	call site: 00151	XXH_read32
5	312	LZ4F_compressBound	call site: 00312	LZ4F_mtCompressBound
5	450	LZ4F_startStream	call site: 00450	LZ4_loadDictHC
4	417	LZ4HC_init_internal	call site: 00417	LZ4MID_fillHTable

Runtime coverage analysis

Covered functions

205

Functions that are reachable but not covered

66

Reachable functions

194

Percentage of reachable functions covered

65.98%

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/file_fuzzer.c	5
ossfuzz/fuzz_data_producer.c	8
lib/lz4file.c	24
lib/lz4frame.c	92
lib/xxhash.c	11
lib/lz4.c	21
lib/lz4hc.c	20
lib/./lz4.c	3

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	98	14.5%
gold	[1:9]	0	0.0%
yellow	[10:29]	3	0.44%
greenyellow	[30:49]	1	0.14%
lawngreen	50+	573	84.8%
All colors	675	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
8	179	LZ4_loadDict_internal	call site: 00179	LZ4_loadDictHC
7	340	LZ4F_mt_acquireInBuff	call site: 00340	LZ4F_invalidateFrame
7	606	LZ4_readLE16	call site: 00606	LZ4_copyMatchExact
6	6	LZ4_XXH32	call site: 00006	XXH_read32
5	168	LZ4F_initLZ4State	call site: 00168	LZ4F_digestRawDict
5	252	LZ4F_mt_begin	call site: 00252	LZ4F_mt_allocState
5	301	LZ4F_mt_submit_internal	call site: 00301	LZ4F_mt_addWorker
5	586	LZ4F_updateDict	call site: 00586	LZ4F_moveDictBeforeTmpOut
4	646	LZ4F_decompress	call site: 00646	LZ4F_moveDictBeforeTmpOut
3	218	LZ4F_startStream	call site: 00218	LZ4_resetStream_fast
3	495	checkInvalidated	call site: 00495	LZ4F_getErrorCode
3	553	LZ4F_decodeHeader	call site: 00553	__assert_fail

Runtime coverage analysis

Covered functions

223

Functions that are reachable but not covered

19

Reachable functions

165

Percentage of reachable functions covered

88.48%

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_frame_stream_fuzzer.c	7
ossfuzz/./fuzz_helpers.h	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	3
lib/lz4frame.c	95
lib/lz4.c	21
lib/lz4hc.c	20
lib/./lz4.c	3

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	280	49.5%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	285	50.4%
All colors	565	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
36	248	LZ4F_compressBlocks_internal	call site: 00248	LZ4F_mt_submitLast
33	188	LZ4F_calloc	call site: 00188	LZ4F_mt_allocState
25	70	LZ4F_initLZ4State	call site: 00070	LZ4F_digestRawDict
24	289	LZ4_XXH32_update	call site: 00289	LZ4F_mt_submit
24	323	LZ4F_st_update	call site: 00323	LZ4F_flushBlock
14	224	LZ4F_compressFrame_usingCDict	call site: 00224	LZ4F_mt_update
10	45	LZ4F_invalidateFrame	call site: 00045	LZ4F_mt_retireOldest
8	179	XXH32_finalize	call site: 00179	LZ4F_mt_begin
8	368	LZ4F_flushBlockPartial	call site: 00368	LZ4F_flushBlock
7	380	LZ4F_emitPending	call site: 00380	LZ4F_invalidateFrame
7	404	LZ4F_compressFrame	call site: 00404	LZ4F_mt_abort
7	487	LZ4_readLE16	call site: 00487	LZ4_copyMatchExact

Runtime coverage analysis

Covered functions

170

Functions that are reachable but not covered

63

Reachable functions

159

Percentage of reachable functions covered

60.38%

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_frame_fuzzer.c	2
ossfuzz/fuzz_data_producer.c	8
lib/lz4frame.c	91
lib/lz4.c	21
lib/lz4hc.c	20
lib/./lz4.c	3
lib/xxhash.c	11
ossfuzz/lz4_helpers.c	1

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
state_loadDictRoundTrip	/src/lz4/ossfuzz/round_trip_stream_fuzzer.c	1	['N/A']	5	0	39	3	2	37	0	2823	2196
LZ4_compress_forceExtDict	/src/lz4/lib/lz4.c	4	['N/A', 'N/A', 'N/A', 'int']	3	0	19214	2576	681	13	0	877	681
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	526	61	20	7	0	61	52

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

Functions statically reachable by fuzzers

281 / 366

Cyclomatic complexity statically reachable by fuzzers

9351 / 9643

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_fuzzer.c

Dictionary

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

ossfuzz/round_trip_frame_uncompressed_fuzzer.c

Dictionary

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

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/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_readLE16', 'LZ4_XXH32', 'LZ4_XXH32_update', 'LZ4_decompress_safe', 'LZ4F_calloc', 'LZ4F_decodeHeader', 'LZ4F_decompress']

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_compress_generic_internal', 'LZ4HC_compress_optimal', 'LZ4_readLE16', 'LZ4HC_countPattern', 'LZ4MID_compress', 'LZ4_NbCommonBytes', 'LZ4_decompress_safe']

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_fastReset', 'LZ4_readLE16', 'LZ4_writeLE16', 'LZ4_decompress_safe']

ossfuzz/round_trip_frame_fuzzer.c

Dictionary

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

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', 'LZ4_resetStreamHC_fast']

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_compress_generic_internal', 'LZ4HC_compress_optimal', 'LZ4_readLE16', 'LZ4HC_countPattern', 'LZ4MID_compress', 'LZ4_writeLE16']

ossfuzz/file_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_compressBlocks_internal', 'LZ4F_headerChecksum', 'LZ4F_freeCompressionContext', 'LZ4F_initLZ4State', 'LZ4F_write', 'LZ4_readLE16', 'LZ4F_flushBlockPartial', 'LZ4F_emitPending', 'LZ4_XXH32', 'LZ4F_compressBound']

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=['LZ4_loadDict_internal', 'LZ4F_mt_acquireInBuff', 'LZ4_readLE16', 'LZ4_XXH32', 'LZ4F_initLZ4State', 'LZ4F_mt_begin', 'LZ4F_mt_submit_internal', 'LZ4F_updateDict', 'LZ4F_decompress', 'LZ4F_startStream']

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_compressBlocks_internal', 'LZ4F_calloc', 'LZ4F_initLZ4State', 'LZ4_XXH32_update', 'LZ4F_st_update', 'LZ4F_compressFrame_usingCDict', 'LZ4F_invalidateFrame', 'XXH32_finalize', 'LZ4F_flushBlockPartial', 'LZ4F_emitPending']

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_frame_fuzzer.c	['compress_frame_fuzzer']	['compress_frame_fuzzer']
/src/lz4/ossfuzz/fuzz_data_producer.c	['round_trip_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'decompress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'compress_fuzzer', 'round_trip_frame_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_fuzzer']	['decompress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'compress_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/decompress_frame_fuzzer.c	['decompress_frame_fuzzer']	['decompress_frame_fuzzer']
/src/lz4/ossfuzz/./fuzz_helpers.h	['round_trip_stream_fuzzer', 'compress_frame_stream_fuzzer']	[]
/src/lz4/lib/lz4file.c	['file_fuzzer']	['file_fuzzer']
/src/lz4/lib/lz4frame.c	['round_trip_frame_uncompressed_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['decompress_frame_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/compress_fuzzer.c	['compress_fuzzer']	['compress_fuzzer']
/src/lz4/ossfuzz/file_fuzzer.c	['file_fuzzer']	['file_fuzzer']
/src/lz4/lib/xxhash.c	['round_trip_frame_uncompressed_fuzzer', 'decompress_frame_fuzzer', 'round_trip_frame_fuzzer', 'round_trip_stream_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['decompress_frame_fuzzer', 'round_trip_stream_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/compress_frame_stream_fuzzer.c	['compress_frame_stream_fuzzer']	['compress_frame_stream_fuzzer']
/src/lz4/ossfuzz/decompress_fuzzer.c	['decompress_fuzzer']	['decompress_fuzzer']
/src/lz4/lib/lz4hc.c	['round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'round_trip_frame_fuzzer', 'round_trip_stream_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['compress_hc_fuzzer', 'round_trip_stream_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']
/src/lz4/lib/lz4.c	['round_trip_fuzzer', 'round_trip_frame_uncompressed_fuzzer', 'decompress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'compress_fuzzer', 'round_trip_frame_fuzzer', 'round_trip_stream_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['decompress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'compress_fuzzer', 'round_trip_stream_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/round_trip_fuzzer.c	['round_trip_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']	['round_trip_hc_fuzzer']
/src/lz4/lib/./lz4.c	['round_trip_frame_uncompressed_fuzzer', 'compress_hc_fuzzer', 'round_trip_frame_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['decompress_fuzzer', 'decompress_frame_fuzzer', 'compress_hc_fuzzer', 'compress_fuzzer', 'round_trip_stream_fuzzer', 'round_trip_hc_fuzzer', 'file_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']
/src/lz4/ossfuzz/round_trip_frame_uncompressed_fuzzer.c	['round_trip_frame_uncompressed_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']	[]
/src/lz4/ossfuzz/lz4_helpers.c	['round_trip_frame_fuzzer', 'compress_frame_stream_fuzzer', 'compress_frame_fuzzer']	['compress_frame_stream_fuzzer', 'compress_frame_fuzzer']

Directories in report

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