High level conclusions

Fuzzers reach 62.92% code coverage.

Fuzzers reach 0.689% of cyclomatic complexity.

Fuzzers reach 1.025% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

33 / 3218

Cyclomatic complexity statically reachable by fuzzers

15 / 2175

Runtime code coverage of functions

2025 / 3218

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: translate

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	525	68.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	247	31.9%
All colors	772	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
153	249	FuzzSmithConfig::arbitrary	call site: 00249	FuzzInput::arbitrary
52	191	ModuleParser::process_types	call site: 00191	FuzzInput::arbitrary
34	637	ModuleParser::consume_buffer	call site: 00637	impl_try_truncate_into
20	674	ModuleParser::parse_buffered_unchecked	call site: 00674	StoreInner::try_resolve_memory
17	39	Config::default_features	call site: 00039	impl_try_truncate_into
16	2	FuzzModule::wasm	call site: 00002	impl_try_truncate_into
16	573	ModuleParser::process_exports	call site: 00573	impl_try_truncate_into
14	128	Module::validate	call site: 00128	fuzz_target
12	511	TableType::from_wasmparser	call site: 00511
11	447	ModuleParser::process_imports	call site: 00447	HeadVec::push
9	61	Engine::new	call site: 00061
8	757	ModuleParser::parse_buffered_impl	call site: 00757	Module::new_unchecked

Runtime coverage analysis

Covered functions

8632

Functions that are reachable but not covered

12

Reachable functions

45

Percentage of reachable functions covered

73.33%

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
fuzz/fuzz_targets/translate.rs	11
crates/fuzz/src/module.rs	3
crates/core/src/value.rs	7
crates/c_api/src/global.rs	10
crates/c_api/src/val.rs	6
crates/wasmi/src/engine/config.rs	2
crates/collections/src/string_interner.rs	7
crates/core/src/memory/buffer.rs	1
crates/c_api/src/config.rs	46
crates/cli/src/commands/run.rs	1
crates/core/src/fuel.rs	9
crates/c_api/src/trap.rs	1
crates/wasmi/src/error.rs	1
crates/c_api/src/module.rs	15
crates/c_api/src/engine.rs	2
crates/wasmi/src/module/parser/buffered.rs	36
crates/wasmi/src/engine/translator/func/utils.rs	1
crates/c_api/src/store.rs	2
fuzz/fuzz_targets/execute.rs	33
crates/wasmi/src/module/parser/mod.rs	66
crates/collections/src/set.rs	8
crates/core/src/limiter.rs	2
crates/wasmi/src/store/id.rs	1
crates/wasmi/src/reftype.rs	2
crates/c_api/src/ref.rs	2
fuzz/fuzz_targets/differential.rs	7
crates/core/src/memory/access.rs	5
crates/fuzz/src/value.rs	7
crates/fuzz/src/config.rs	2
crates/c_api/src/func.rs	4
crates/wasmi/src/module/utils.rs	10
crates/wasmi/src/module/builder.rs	12
crates/wasmi/src/engine/mod.rs	3
crates/collections/src/head_vec.rs	2
crates/core/src/table/ty.rs	1
crates/c_api/src/vec.rs	2
crates/c_api/src/memory.rs	3
crates/core/src/memory/mod.rs	3
crates/wasmi/src/func/caller.rs	1
crates/wasmi/src/store/inner.rs	6
crates/wasmi/src/store/error.rs	1
crates/ir/src/span.rs	2
crates/collections/src/hash.rs	1
crates/wasmi/src/engine/code_map.rs	3
crates/core/src/memory/ty.rs	1

Fuzzer: execute

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	935	73.8%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	331	26.1%
All colors	1266	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
82	911	LinkerError::missing_definition	call site: 00911	fuzz_target
63	839	proc_macro::TokenStream::element	call site: 00839	impl_try_truncate_into
60	1088	StoreInner::try_resolve_memory_mut	call site: 01088	wasm_val_t::from
56	1022	ResourceLimiterRef::as_resource_limiter	call site: 01022	wasm_val_t::to_val
50	322	FuzzSmithConfig::allow_execution	call site: 00322	FuzzInput::arbitrary
47	791	Module::func_types_cloned	call site: 00791	impl_try_truncate_into
45	1220	ModuleParser::parse_buffered_data	call site: 01220	Linker::instantiate_and_start
40	749	ModuleParser::parse_buffered_unchecked	call site: 00749	Linker::instantiate_and_start
24	116	StoreLimitsBuilder::new	call site: 00116	fuzz_target
23	259	ModuleParser::process_types	call site: 00259	wasm_global_t::try_from
23	723	StoreInner::try_resolve_memory	call site: 00723	Module::validate
17	452	Error::from	call site: 00452	Error::from

Runtime coverage analysis

Covered functions

11133

Functions that are reachable but not covered

26

Reachable functions

98

Percentage of reachable functions covered

73.47%

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
fuzz/fuzz_targets/execute.rs	53
crates/fuzz/src/module.rs	3
crates/core/src/value.rs	7
crates/c_api/src/global.rs	20
crates/c_api/src/val.rs	11
crates/wasmi/src/engine/config.rs	2
crates/collections/src/string_interner.rs	7
crates/core/src/memory/buffer.rs	1
crates/c_api/src/config.rs	85
crates/cli/src/commands/run.rs	1
crates/core/src/fuel.rs	9
crates/c_api/src/trap.rs	1
crates/wasmi/src/error.rs	1
crates/c_api/src/memory.rs	6
crates/c_api/src/store.rs	5
crates/core/src/memory/ty.rs	5
crates/c_api/src/engine.rs	2
crates/core/src/limiter.rs	2
crates/c_api/src/error.rs	3
crates/c_api/src/module.rs	28
crates/wasmi/src/module/parser/buffered.rs	36
crates/wasmi/src/engine/translator/func/utils.rs	1
crates/wasmi/src/engine/code_map.rs	3
crates/wasmi/src/module/parser/mod.rs	66
crates/collections/src/set.rs	8
crates/wasmi/src/store/id.rs	1
crates/wasmi/src/reftype.rs	2
crates/c_api/src/ref.rs	2
fuzz/fuzz_targets/differential.rs	5
crates/core/src/memory/access.rs	5
crates/fuzz/src/value.rs	7
crates/fuzz/src/config.rs	2
crates/c_api/src/func.rs	30
crates/wasmi/src/module/utils.rs	10
crates/wasmi/src/module/builder.rs	12
crates/wasmi/src/engine/mod.rs	3
crates/collections/src/head_vec.rs	2
crates/core/src/table/ty.rs	1
crates/c_api/src/vec.rs	2
crates/core/src/memory/mod.rs	6
crates/wasmi/src/func/caller.rs	2
crates/wasmi/src/store/inner.rs	10
crates/wasmi/src/store/error.rs	1
crates/ir/src/span.rs	2
crates/wasmi/src/linker.rs	27
crates/wasmi/src/module/mod.rs	2
crates/c_api/src/types/global.rs	1
crates/c_api/macro/lib.rs	8
crates/c_api/src/types/table.rs	1
crates/wasmi/tests/integration/resource_limiter.rs	3
crates/c_api/src/instance.rs	9
crates/collections/src/map.rs	2
crates/c_api/src/utils.rs	1
crates/collections/src/hash.rs	1

Fuzzer: differential

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	882	70.5%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	369	29.4%
All colors	1251	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
61	1122	proc_macro::TokenStream::element	call site: 01122	impl_try_truncate_into
57	445	StoreInner::try_resolve_memory_mut	call site: 00445	wasm_val_t::from
56	373	ResourceLimiterRef::as_resource_limiter	call site: 00373	wasm_val_t::to_val
54	1188	LinkerError::missing_definition	call site: 01188	impl_try_truncate_into
41	1039	ModuleParser::parse_buffered_impl	call site: 01039	Linker::instantiate_and_start
39	1082	Module::func_types_cloned	call site: 01082	impl_try_truncate_into
28	701	FuzzState::init_params	call site: 00701	Error::from
21	238	FuzzSmithConfig::allow_execution	call site: 00238	FuzzInput::arbitrary
19	260	FuzzModule::ensure_termination	call site: 00260	fuzz_target
18	174	ResourceLimiterRef::as_resource_limiter	call site: 00174	impl_try_truncate_into
17	155	WasmSource::into_bytes	call site: 00155	wasm_global_t::try_from
17	954	ModuleParser::consume_buffer	call site: 00954	ModuleParser::process_invalid_payload

Runtime coverage analysis

Covered functions

12562

Functions that are reachable but not covered

10

Reachable functions

71

Percentage of reachable functions covered

85.92%

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
fuzz/fuzz_targets/differential.rs	48
crates/fuzz/src/module.rs	3
crates/core/src/value.rs	8
crates/c_api/src/val.rs	11
crates/wasmi/src/engine/config.rs	6
crates/collections/src/string_interner.rs	7
crates/core/src/memory/buffer.rs	1
crates/c_api/src/config.rs	85
crates/c_api/src/trap.rs	1
crates/wasmi/src/error.rs	1
crates/c_api/src/memory.rs	6
crates/c_api/src/store.rs	3
fuzz/fuzz_targets/execute.rs	25
crates/c_api/src/instance.rs	9
crates/wasmi/src/func/caller.rs	2
crates/cli/src/context.rs	6
crates/c_api/src/vec.rs	2
crates/c_api/macro/lib.rs	8
crates/c_api/src/global.rs	24
crates/collections/src/set.rs	8
crates/core/src/limiter.rs	2
crates/wasmi/src/engine/translator/func/utils.rs	1
crates/wasmi/src/store/id.rs	1
crates/core/src/memory/access.rs	5
crates/fuzz/src/value.rs	7
crates/fuzz/src/config.rs	2
crates/c_api/src/func.rs	30
crates/wasmi/src/engine/code_map.rs	3
crates/collections/src/map.rs	2
crates/wasmi/src/module/mod.rs	2
crates/c_api/src/utils.rs	1
crates/core/src/memory/mod.rs	6
crates/wasmi/src/store/inner.rs	10
crates/wasmi/src/store/error.rs	1
crates/fuzz/src/oracle/exports.rs	1
crates/fuzz/src/oracle/wasmi_v1.rs	6
crates/core/src/simd.rs	1
crates/wasmi/src/limits.rs	1
crates/core/src/memory/ty.rs	5
crates/c_api/src/engine.rs	2
crates/wasmi/src/module/parser/buffered.rs	36
crates/wasmi/src/module/parser/mod.rs	66
crates/wasmi/src/reftype.rs	2
crates/c_api/src/ref.rs	2
crates/wasmi/src/module/utils.rs	10
crates/wasmi/src/module/builder.rs	12
crates/wasmi/src/engine/mod.rs	3
crates/collections/src/head_vec.rs	2
crates/core/src/table/ty.rs	1
crates/collections/src/hash.rs	1
crates/wasmi/src/linker.rs	27
crates/c_api/src/module.rs	13
crates/c_api/src/types/global.rs	1
crates/c_api/src/types/table.rs	1
crates/wasmi/tests/integration/resource_limiter.rs	3

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity

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

Functions statically reachable by fuzzers

33 / 3218

Cyclomatic complexity statically reachable by fuzzers

15 / 2175

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.

fuzz/fuzz_targets/translate.rs

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=['FuzzSmithConfig::arbitrary', 'ModuleParser::process_types', 'ModuleParser::consume_buffer', 'ModuleParser::parse_buffered_unchecked', 'Config::default_features', 'FuzzModule::wasm', 'ModuleParser::process_exports', 'Module::validate', 'TableType::from_wasmparser', 'ModuleParser::process_imports']

fuzz/fuzz_targets/execute.rs

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=['LinkerError::missing_definition', 'proc_macro::TokenStream::element', 'StoreInner::try_resolve_memory_mut', 'ResourceLimiterRef::as_resource_limiter', 'FuzzSmithConfig::allow_execution', 'Module::func_types_cloned', 'ModuleParser::parse_buffered_data', 'ModuleParser::parse_buffered_unchecked', 'StoreLimitsBuilder::new', 'ModuleParser::process_types']

fuzz/fuzz_targets/differential.rs

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=['proc_macro::TokenStream::element', 'StoreInner::try_resolve_memory_mut', 'ResourceLimiterRef::as_resource_limiter', 'LinkerError::missing_definition', 'ModuleParser::parse_buffered_impl', 'Module::func_types_cloned', 'FuzzState::init_params', 'FuzzSmithConfig::allow_execution', 'FuzzModule::ensure_termination']

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
wasmi_ir::op::Op as wasmi::engine::translator::comparator::TryIntoCmpSelectInstr::try_into_cmp_select_instr::wasmi::engine::translator::func::FuncTranslator::try_fuse_select::{closure:#0}	106	51	48.11%
wasmi_ir::op::Op as wasmi::engine::translator::comparator::CompareResult::compare_result	97	42	43.29%
wasmi_ir::op::Op::result_ref	602	274	45.51%
wasmi::linker::Linkerwasmi::limits::StoreLimits::process_import::&mut &mut wasmi::store::Storewasmi::limits::StoreLimits	40	12	30.0%
wasmi::module::Module::extract_imports::alloc::vec::Vecwasmi::instance::exports::Extern, &&mut wasmi::store::Storewasmi::limits::StoreLimits	62	15	24.19%
differential::FuzzState::assert_memories_match	32	7	21.87%
cranelift_assembler_x64::inst::Instcranelift_codegen::isa::x64::inst::external::CraneliftRegisters::is_available::&cranelift_codegen::isa::x64::inst::EmitInfo	1074	355	33.05%
cranelift_assembler_x64::inst::Instcranelift_codegen::isa::x64::inst::external::CraneliftRegisters::visit::cranelift_codegen::isa::x64::inst::external::RegallocVisitorcranelift_codegen::machinst::reg::OperandCollectorcranelift_codegen::machinst::vcode::VCodeBuildercranelift_codegen::isa::x64::lower::isle::generated_code::MInst::collect_operands::{closure:#0}	1074	321	29.88%
cranelift_assembler_x64::inst::Instcranelift_codegen::isa::x64::inst::external::CraneliftRegisters::visit::cranelift_codegen::isa::x64::inst::external::RegallocVisitorcranelift_codegen::machinst::vcode::VCodecranelift_codegen::isa::x64::lower::isle::generated_code::MInst::emit::{closure:#3}	1074	321	29.88%
cranelift_assembler_x64::inst::Instcranelift_codegen::isa::x64::inst::external::CraneliftRegisters::encode::cranelift_codegen::isa::x64::inst::external::AsmCodeSink	1074	366	34.07%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_cmove::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	155	48	30.96%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_lower::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	8084	4325	53.50%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_sar::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	57	28	49.12%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_shl::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	57	28	49.12%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_shr::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	57	30	52.63%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_load::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	48	22	45.83%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_rotl::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	59	24	40.67%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_rotr::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	57	22	38.59%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_emit_fcmp::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	180	76	42.22%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_round::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	95	28	29.47%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_with_flags::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	82	31	37.80%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_pcmpgt::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	48	18	37.5%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_sbb_raw::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	66	21	31.81%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_sub_mem::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	91	14	15.38%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_x64_xor_mem::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	97	49	50.51%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_is_nonzero_band::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	82	38	46.34%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_f32x4_insertlane::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	33	13	39.39%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_all_ones_or_all_zeros::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	69	27	39.13%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_with_flags_side_effect::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	51	15	29.41%
cranelift_codegen::isa::x64::lower::isle::generated_code::constructor_consumes_flags_return_last::cranelift_codegen::machinst::isle::IsleContextcranelift_codegen::isa::x64::lower::isle::generated_code::MInst, cranelift_codegen::isa::x64::X64Backend	38	19	50.0%

New fuzzers

The below fuzzers are templates and suggestions for how to target the set of optimal functions above

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/wasmi/crates/wasmi/src/store/typeid.rs	[]	[]
/src/wasmi/crates/cli/tests/run.rs	[]	[]
/src/wasmi/crates/c_api/src/instance.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/wasmi/src/store/context.rs	[]	[]
/src/wasmi/crates/wasmi/src/tests.rs	[]	[]
/src/wasmi/crates/c_api/src/types/global.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/wasmi/tests/integration/resumable_call.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/func_types.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/instantiate/tests.rs	[]	[]
/src/wasmi/crates/fuzz/src/config.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/collections/src/hash.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/module/parser/mod.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/c_api/src/table.rs	[]	[]
/src/wasmi/crates/fuzz/src/oracle/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/func/typed_func.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/limits/stack.rs	[]	[]
/src/wasmi/crates/wasmi/tests/integration/instantitation.rs	[]	[]
/src/wasmi/crates/c_api/src/func.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/operand.rs	[]	[]
/src/wasmi/crates/c_api/src/error.rs	['execute']	['execute']
/src/wasmi/crates/wasmi/src/func/ty.rs	[]	[]
/src/wasmi/crates/wasmi/src/store/pruned.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/simd/mod.rs	[]	[]
/src/wasmi/fuzz/fuzz_targets/differential.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/collections/src/map.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/ir/build.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/dispatch/backend/tail.rs	[]	[]
/src/wasmi/crates/c_api/src/types/import.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/error.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/comparator.rs	[]	[]
/src/wasmi/crates/wast/tests/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/eval.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/dispatch/backend/loop.rs	[]	[]
/src/wasmi/crates/wasi/src/sync/snapshots/preview_1.rs	[]	[]
/src/wasmi/crates/c_api/src/types/table.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/c_api/src/module.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/tests/integration/func.rs	[]	[]
/src/wasmi/crates/c_api/src/types/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/func/error.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/simd/op.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/limits/engine.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/control.rs	[]	[]
/src/wasmi/crates/wasmi/src/func/caller.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/linker.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/wasmi/src/instance/exports.rs	[]	[]
/src/wasmi/crates/wasmi/src/memory/ty.rs	[]	[]
/src/wasmi/crates/wasi/src/guest_memory.rs	[]	[]
/src/wasmi/crates/fuzz/src/error.rs	[]	[]
/src/wasmi/crates/wasmi/src/foreach_tuple.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/mod.rs	[]	[]
/src/wasmi/crates/fuzz/src/oracle/wasmi.rs	[]	[]
/src/wasmi/crates/c_api/src/extern.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/custom_section.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/config.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/code_map.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/fuzz/src/module.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/module/mod.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/core/src/memory/ty.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/module/parser/buffered.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/instance/builder.rs	[]	[]
/src/wasmi/crates/wasmi/tests/integration/fuel_consumption.rs	[]	[]
/src/wasmi/crates/c_api/src/utils.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/ir/src/index.rs	[]	[]
/src/wasmi/crates/cli/src/commands/mod.rs	[]	[]
/src/wasmi/crates/c_api/src/types/extern.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/inout.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/global.rs	[]	[]
/src/wasmi/crates/wasmi/tests/integration/multi_memory.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/mod.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/collections/src/arena/dedup.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/mod.rs	[]	[]
/src/wasmi/crates/fuzz/src/oracle/wasmi_v1.rs	['differential']	['differential']
/src/wasmi/crates/c_api/src/frame.rs	[]	[]
/src/wasmi/crates/core/src/memory/buffer.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/core/src/trap.rs	[]	[]
/src/wasmi/crates/cli/src/commands/wast.rs	[]	[]
/src/wasmi/crates/core/src/memory/mod.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/ir/src/span.rs	['translate', 'execute']	['translate', 'execute']
/src/wasmi/crates/wasmi/tests/integration/resource_limiter.rs	['execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/wasmi/tests/integration/fuel_metering.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/read.rs	[]	[]
/src/wasmi/crates/wast/src/lib.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/op.rs	[]	[]
/src/wasmi/crates/wasmi/src/limits.rs	['differential']	['differential']
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/operands.rs	[]	[]
/src/wasmi/crates/wasmi/src/reftype.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/translator/utils.rs	[]	[]
/src/wasmi/crates/collections/src/arena/mod.rs	[]	[]
/src/wasmi/crates/core/src/table/raw.rs	[]	[]
/src/wasmi/crates/c_api/src/trap.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/c_api/src/types/func.rs	[]	[]
/src/wasmi/crates/c_api/src/store.rs	['translate', 'execute', 'differential']	['execute', 'differential']
/src/wasmi/crates/ir/src/decode/mod.rs	[]	[]
/src/wasmi/crates/fuzz/src/crash_inputs.rs	[]	[]
/src/wasmi/crates/core/src/fuel.rs	['translate', 'execute']	['translate', 'execute']
/src/wasmi/crates/ir/src/primitive.rs	[]	[]
/src/wasmi/crates/wasmi/tests/integration/host_calls_wasm.rs	[]	[]
/src/wasmi/crates/c_api/src/global.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/collections/src/set.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/resumable.rs	[]	[]
/src/wasmi/crates/wasmi/src/handle.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/visit.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/mod.rs	[]	[]
/src/wasmi/crates/collections/src/head_vec.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/instance/tests.rs	[]	[]
/src/wasmi/crates/c_api/src/ref.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/executor/handler/exec.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/utils.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/tests/integration/call_host_via_engine.rs	[]	[]
/src/wasmi/crates/core/src/typed.rs	[]	[]
/src/wasmi/crates/core/src/raw.rs	[]	[]
/src/wasmi/crates/core/src/index_ty.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/locals.rs	[]	[]
/src/wasmi/crates/core/src/global.rs	[]	[]
/src/wasmi/crates/core/src/wasm.rs	[]	[]
/src/wasmi/crates/core/src/value.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/tests/integration/host_call_compilation.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/utils.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/utils.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/labels.rs	[]	[]
/src/wasmi/crates/wasmi/src/store/error.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/collections/src/arena/error.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/cell.rs	[]	[]
/src/wasmi/crates/wasmi/src/store/id.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/ir/src/decode/op.rs	[]	[]
/src/wasmi/crates/wasmi/src/memory/mod.rs	[]	[]
/src/wasmi/crates/core/src/float.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/limits/tests.rs	[]	[]
/src/wasmi/crates/c_api/src/engine.rs	['translate', 'execute', 'differential']	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/state.rs	[]	[]
/src/wasmi/crates/core/src/memory/error.rs	[]	[]
/src/wasmi/crates/ir/src/op.rs	[]	[]
/src/wasmi/crates/core/src/table/ty.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/fuzz/src/value.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/core/src/limiter.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/benches/benches.rs	[]	[]
/src/wasmi/crates/c_api/src/memory.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/table/ty.rs	[]	[]
/src/wasmi/crates/core/src/table/error.rs	[]	[]
/src/wasmi/crates/wasmi/src/value.rs	[]	[]
/src/wasmi/fuzz/fuzz_targets/execute.rs	['translate', 'execute', 'differential']	['execute']
/src/wasmi/crates/wasmi/tests/integration/call_hook.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/builder.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/core/src/func_type.rs	[]	[]
/src/wasmi/crates/collections/src/tests.rs	[]	[]
/src/wasmi/crates/collections/src/arena/component_vec.rs	[]	[]
/src/wasmi/crates/cli/src/context.rs	['differential']	['differential']
/src/wasmi/crates/fuzz/src/oracle/wasmtime.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/simd/visit.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/exec/simd.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/driver.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/encoder.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/dispatch/mod.rs	[]	[]
/src/wasmi/crates/cli/src/commands/run.rs	['translate', 'execute']	['translate', 'execute']
/src/wasmi/crates/wasmi/src/module/export.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/instantiate/mod.rs	[]	[]
/src/wasmi/crates/ir/src/encode.rs	[]	[]
/src/wasmi/crates/core/src/table/tests.rs	[]	[]
/src/wasmi/crates/wasmi/src/global.rs	[]	[]
/src/wasmi/crates/c_api/src/foreign.rs	[]	[]
/src/wasmi/crates/cli/src/tests.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/utils.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/engine/translator/func/layout.rs	[]	[]
/src/wasmi/crates/wasmi/src/func/mod.rs	[]	[]
/src/wasmi/crates/collections/src/string_interner/detail.rs	[]	[]
/src/wasmi/crates/wasmi/src/instance/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/mod.rs	[]	[]
/src/wasmi/crates/c_api/src/val.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/core/src/memory/access.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/func/into_func.rs	[]	[]
/src/wasmi/crates/core/src/table/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/exec/macros.rs	[]	[]
/src/wasmi/crates/c_api/macro/lib.rs	['execute', 'differential']	[]
/src/wasmi/crates/wasmi/benches/bench/mod.rs	[]	[]
/src/wasmi/crates/c_api/src/vec.rs	['translate', 'execute', 'differential']	[]
/src/wasmi/crates/wasmi/tests/integration/host_call_instantiation.rs	[]	[]
/src/wasmi/crates/ir/src/opcode.rs	[]	[]
/src/wasmi/crates/wasmi/src/store/inner.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/core/src/host_error.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/data.rs	[]	[]
/src/wasmi/crates/wasmi/src/error.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/wasmi/src/table/element.rs	[]	[]
/src/wasmi/crates/wasi/tests/wasi_wat.rs	[]	[]
/src/wasmi/crates/c_api/src/types/memory.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/init_expr.rs	[]	[]
/src/wasmi/crates/wasmi/src/memory/data.rs	[]	[]
/src/wasmi/crates/core/src/memory/tests.rs	[]	[]
/src/wasmi/crates/core/src/table/element.rs	[]	[]
/src/wasmi/crates/collections/src/string_interner.rs	['translate', 'execute', 'differential']	['translate', 'execute', 'differential']
/src/wasmi/crates/cli/src/utils.rs	[]	[]
/src/wasmi/crates/fuzz/src/oracle/exports.rs	['differential']	['differential']
/src/wasmi/crates/core/src/simd.rs	['differential']	['differential']
/src/wasmi/crates/c_api/src/config.rs	['translate', 'execute', 'differential']	[]
/src/wasmi/crates/wasmi/src/table/mod.rs	[]	[]
/src/wasmi/crates/cli/src/main.rs	[]	[]
/src/wasmi/crates/wasmi/src/store/mod.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/block_type.rs	[]	[]
/src/wasmi/crates/wasmi/tests/integration/host_call_error.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/instantiate/error.rs	[]	[]
/src/wasmi/crates/cli/src/display.rs	[]	[]
/src/wasmi/crates/c_api/src/types/export.rs	[]	[]
/src/wasmi/crates/core/src/hint.rs	[]	[]
/src/wasmi/fuzz/fuzz_targets/translate.rs	['translate']	[]
/src/wasmi/crates/wasmi/src/module/element.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/translator/func/locals.rs	[]	[]
/src/wasmi/crates/c_api/src/types/val.rs	[]	[]
/src/wasmi/crates/wasmi/src/engine/executor/handler/func.rs	[]	[]
/src/wasmi/crates/wasmi/src/module/import.rs	[]	[]

Directories in report

Directory
/src/wasmi/crates/c_api/macro/
/src/wasmi/crates/wasmi/tests/integration/
/src/wasmi/crates/fuzz/src/
/src/wasmi/crates/wasmi/src/memory/
/src/wasmi/crates/core/src/
/src/wasmi/crates/wasmi/src/engine/translator/func/stack/
/src/wasmi/fuzz/fuzz_targets/
/src/wasmi/crates/wasmi/src/engine/translator/func/
/src/wasmi/crates/c_api/src/types/
/src/wasmi/crates/collections/src/string_interner/
/src/wasmi/crates/wasmi/src/module/parser/
/src/wasmi/crates/wasmi/src/engine/executor/
/src/wasmi/crates/wasmi/src/table/
/src/wasmi/crates/wasmi/src/module/
/src/wasmi/crates/wasmi/src/engine/executor/handler/exec/
/src/wasmi/crates/core/src/table/
/src/wasmi/crates/ir/src/
/src/wasmi/crates/wasmi/src/engine/translator/func/simd/
/src/wasmi/crates/wasmi/benches/
/src/wasmi/crates/wasmi/src/engine/executor/handler/dispatch/
/src/wasmi/crates/collections/src/arena/
/src/wasmi/crates/wasmi/src/instance/
/src/wasmi/crates/wasi/src/
/src/wasmi/crates/core/src/memory/
/src/wasmi/crates/wasmi/src/func/
/src/wasmi/crates/wasmi/src/engine/limits/
/src/wasmi/crates/cli/tests/
/src/wasmi/crates/wasi/src/sync/snapshots/
/src/wasmi/crates/wasmi/src/store/
/src/wasmi/crates/c_api/src/
/src/wasmi/crates/fuzz/src/oracle/
/src/wasmi/crates/wast/src/
/src/wasmi/crates/wasi/tests/
/src/wasmi/crates/wast/tests/
/src/wasmi/crates/cli/src/commands/
/src/wasmi/crates/collections/src/
/src/wasmi/crates/cli/src/
/src/wasmi/crates/wasmi/src/module/instantiate/
/src/wasmi/crates/ir/src/decode/
/src/wasmi/crates/wasmi/src/engine/translator/
/src/wasmi/crates/wasmi/src/engine/executor/handler/dispatch/backend/
/src/wasmi/crates/wasmi/src/engine/executor/handler/
/src/wasmi/crates/wasmi/benches/bench/
/src/wasmi/crates/ir/
/src/wasmi/crates/wasmi/src/engine/
/src/wasmi/crates/wasmi/src/

This section shows a list of 3rd party function calls and their relative coverage information. By static analysis of the target project code, all of the 3rd party function call and their caller information, including the source file and line number that initiate the call are captured. The caller source code file and line number are shown in column 2 while column 1 is the function name of the 3rd party function call. Each occurrent of the 3rd party function call will occuply a separate row. Column 3 of each row indicate if the 3rd party call in the source file line is unreachable. Column 4 lists all fuzzers that have covered that particular system call in that specific location (source file and line)during their dynamic fuzzing.

Function in each files in report

Target sink	Callsite location	Reached by fuzzer	Covered by Fuzzers