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Cranelift CLIF-level differential fuzzer (#3038)

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* cranelift: Initial fuzzer implementation

* cranelift: Generate multiple test cases in fuzzer

* cranelift: Separate function generator in fuzzer

* cranelift: Insert random instructions in fuzzer

* cranelift: Rename gen_testcase

* cranelift: Implement div for unsigned values in interpreter

* cranelift: Run all test cases in fuzzer

* cranelift: Comment options in function_runner

* cranelift: Improve fuzzgen README.md

* cranelift: Fuzzgen remove unused variable

* cranelift: Fuzzer code style fixes

Thanks! @bjorn3

* cranelift: Fix nits in CLIF fuzzer

Thanks @cfallin!

* cranelift: Implement Arbitrary for TestCase

* cranelift: Remove gen_testcase

* cranelift: Move fuzzers to wasmtime fuzz directory

* cranelift: CLIF-Fuzzer ignore tests that produce traps

* cranelift: CLIF-Fuzzer create new fuzz target to validate generated testcases

* cranelift: Store clif-fuzzer config in a separate struct

* cranelift: Generate variables upfront per function

* cranelift: Prevent publishing of fuzzgen crate
This commit is contained in:
Afonso Bordado
2021-07-01 14:32:01 +01:00
committed by GitHub
parent a603fc5bd5
commit 7453bd5f0d
14 changed files with 732 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
Cargo.lock generated
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@@ -640,6 +640,16 @@ dependencies = [
"target-lexicon",
]
[[package]]
name = "cranelift-fuzzgen"
version = "0.75.0"
dependencies = [
"anyhow",
"arbitrary",
"cranelift",
"rand 0.8.3",
]
[[package]]
name = "cranelift-interpreter"
version = "0.75.0"
@@ -747,6 +757,7 @@ dependencies = [
"cranelift-entity",
"cranelift-filetests",
"cranelift-frontend",
"cranelift-fuzzgen",
"cranelift-interpreter",
"cranelift-jit",
"cranelift-module",
@@ -3676,6 +3687,9 @@ name = "wasmtime-fuzz"
version = "0.0.0"
dependencies = [
"cranelift-codegen",
"cranelift-filetests",
"cranelift-fuzzgen",
"cranelift-interpreter",
"cranelift-reader",
"cranelift-wasm",
"libfuzzer-sys",

1
cranelift/Cargo.toml
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@@ -29,6 +29,7 @@ cranelift-object = { path = "object", version = "0.75.0" }
cranelift-jit = { path = "jit", version = "0.75.0" }
cranelift-preopt = { path = "preopt", version = "0.75.0" }
cranelift = { path = "umbrella", version = "0.75.0" }
cranelift-fuzzgen = { path = "fuzzgen", version = "0.75.0" }
filecheck = "0.5.0"
log = "0.4.8"
termcolor = "1.1.2"

4
cranelift/filetests/src/function_runner.rs
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@@ -91,13 +91,17 @@ impl SingleFunctionCompiler {
}
}
/// Compilation Error when compiling a function.
#[derive(Error, Debug)]
pub enum CompilationError {
/// This Target ISA is invalid for the current host.
#[error("Cross-compilation not currently supported; use the host's default calling convention \
or remove the specified calling convention in the function signature to use the host's default.")]
InvalidTargetIsa,
/// Cranelift codegen error.
#[error("Cranelift codegen error")]
CodegenError(#[from] CodegenError),
/// Memory mapping error.
#[error("Memory mapping error")]
IoError(#[from] std::io::Error),
}

2
cranelift/filetests/src/lib.rs
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@@ -30,7 +30,7 @@ use std::path::Path;
use std::time;
mod concurrent;
mod function_runner;
pub mod function_runner;
mod match_directive;
mod runner;
mod runone;

18
cranelift/fuzzgen/Cargo.toml Normal file
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@@ -0,0 +1,18 @@
[package]
name = "cranelift-fuzzgen"
version = "0.75.0"
authors = ["The Wasmtime Project Developers"]
description = "Cranelift module generator"
license = "Apache-2.0 WITH LLVM-exception"
repository = "https://github.com/bytecodealliance/wasmtime"
readme = "README.md"
edition = "2018"
publish = false
[dependencies]
cranelift = { path = "../umbrella", version = "0.75.0" }
anyhow = "1.0.19"
arbitrary = "1.0.0"
rand = "0.8.0"

220
cranelift/fuzzgen/LICENSE Normal file
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@@ -0,0 +1,220 @@
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3
cranelift/fuzzgen/README.md Normal file
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@@ -0,0 +1,3 @@
# `cranelift-fuzzgen`
This crate implements a generator to create random Cranelift modules.

24
cranelift/fuzzgen/src/config.rs Normal file
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@@ -0,0 +1,24 @@
use std::ops::RangeInclusive;
/// Holds the range of acceptable values to use during the generation of testcases
pub struct Config {
pub test_case_inputs: RangeInclusive<usize>,
pub signature_params: RangeInclusive<usize>,
pub signature_rets: RangeInclusive<usize>,
pub instructions_per_block: RangeInclusive<usize>,
/// Number of variables that we allocate per function
/// This value does not include the signature params
pub vars_per_function: RangeInclusive<usize>,
}
impl Default for Config {
fn default() -> Self {
Config {
test_case_inputs: 1..=10,
signature_params: 0..=16,
signature_rets: 0..=16,
instructions_per_block: 0..=64,
vars_per_function: 0..=16,
}
}
}

253
cranelift/fuzzgen/src/function_generator.rs Normal file
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@@ -0,0 +1,253 @@
use crate::config::Config;
use anyhow::Result;
use arbitrary::Unstructured;
use cranelift::codegen::ir::types::*;
use cranelift::codegen::ir::{AbiParam, ExternalName, Function, Opcode, Signature, Type, Value};
use cranelift::codegen::isa::CallConv;
use cranelift::frontend::{FunctionBuilder, FunctionBuilderContext, Variable};
use cranelift::prelude::{EntityRef, InstBuilder};
fn insert_opcode_arity_0(
_fgen: &mut FunctionGenerator,
builder: &mut FunctionBuilder,
opcode: Opcode,
_args: &'static [Type],
_rets: &'static [Type],
) -> Result<()> {
builder.ins().NullAry(opcode, INVALID);
Ok(())
}
fn insert_opcode_arity_2(
fgen: &mut FunctionGenerator,
builder: &mut FunctionBuilder,
opcode: Opcode,
args: &'static [Type],
rets: &'static [Type],
) -> Result<()> {
let arg0 = fgen.get_variable_of_type(args[0])?;
let arg0 = builder.use_var(arg0);
let arg1 = fgen.get_variable_of_type(args[1])?;
let arg1 = builder.use_var(arg1);
let typevar = rets[0];
let (inst, dfg) = builder.ins().Binary(opcode, typevar, arg0, arg1);
let results = dfg.inst_results(inst).to_vec();
for (val, ty) in results.into_iter().zip(rets) {
let var = fgen.get_variable_of_type(*ty)?;
builder.def_var(var, val);
}
Ok(())
}
type OpcodeInserter = fn(
fgen: &mut FunctionGenerator,
builder: &mut FunctionBuilder,
Opcode,
&'static [Type],
&'static [Type],
) -> Result<()>;
// TODO: Derive this from the `cranelift-meta` generator.
const OPCODE_SIGNATURES: &'static [(
Opcode,
&'static [Type], // Args
&'static [Type], // Rets
OpcodeInserter,
)] = &[
(Opcode::Nop, &[], &[], insert_opcode_arity_0),
// Iadd
(Opcode::Iadd, &[I8, I8], &[I8], insert_opcode_arity_2),
(Opcode::Iadd, &[I16, I16], &[I16], insert_opcode_arity_2),
(Opcode::Iadd, &[I32, I32], &[I32], insert_opcode_arity_2),
(Opcode::Iadd, &[I64, I64], &[I64], insert_opcode_arity_2),
// Isub
(Opcode::Isub, &[I8, I8], &[I8], insert_opcode_arity_2),
(Opcode::Isub, &[I16, I16], &[I16], insert_opcode_arity_2),
(Opcode::Isub, &[I32, I32], &[I32], insert_opcode_arity_2),
(Opcode::Isub, &[I64, I64], &[I64], insert_opcode_arity_2),
// Imul
(Opcode::Imul, &[I8, I8], &[I8], insert_opcode_arity_2),
(Opcode::Imul, &[I16, I16], &[I16], insert_opcode_arity_2),
(Opcode::Imul, &[I32, I32], &[I32], insert_opcode_arity_2),
(Opcode::Imul, &[I64, I64], &[I64], insert_opcode_arity_2),
// Udiv
(Opcode::Udiv, &[I8, I8], &[I8], insert_opcode_arity_2),
(Opcode::Udiv, &[I16, I16], &[I16], insert_opcode_arity_2),
(Opcode::Udiv, &[I32, I32], &[I32], insert_opcode_arity_2),
(Opcode::Udiv, &[I64, I64], &[I64], insert_opcode_arity_2),
// Sdiv
(Opcode::Sdiv, &[I8, I8], &[I8], insert_opcode_arity_2),
(Opcode::Sdiv, &[I16, I16], &[I16], insert_opcode_arity_2),
(Opcode::Sdiv, &[I32, I32], &[I32], insert_opcode_arity_2),
(Opcode::Sdiv, &[I64, I64], &[I64], insert_opcode_arity_2),
];
pub struct FunctionGenerator<'r, 'data>
where
'data: 'r,
{
u: &'r mut Unstructured<'data>,
config: &'r Config,
vars: Vec<(Type, Variable)>,
}
impl<'r, 'data> FunctionGenerator<'r, 'data>
where
'data: 'r,
{
pub fn new(u: &'r mut Unstructured<'data>, config: &'r Config) -> Self {
Self {
u,
config,
vars: vec![],
}
}
fn generate_callconv(&mut self) -> Result<CallConv> {
// TODO: Generate random CallConvs per target
Ok(CallConv::SystemV)
}
fn generate_type(&mut self) -> Result<Type> {
// TODO: It would be nice if we could get these directly from cranelift
let scalars = [
// IFLAGS, FFLAGS,
// B1, B8, B16, B32, B64, B128,
I8, I16, I32, I64,
// I128,
// F32, F64,
// R32, R64,
];
// TODO: vector types
let ty = self.u.choose(&scalars[..])?;
Ok(*ty)
}
fn generate_abi_param(&mut self) -> Result<AbiParam> {
// TODO: Generate more advanced abi params (structs/purposes/extensions/etc...)
let ty = self.generate_type()?;
Ok(AbiParam::new(ty))
}
fn generate_signature(&mut self) -> Result<Signature> {
let callconv = self.generate_callconv()?;
let mut sig = Signature::new(callconv);
for _ in 0..self.u.int_in_range(self.config.signature_params.clone())? {
sig.params.push(self.generate_abi_param()?);
}
for _ in 0..self.u.int_in_range(self.config.signature_rets.clone())? {
sig.returns.push(self.generate_abi_param()?);
}
Ok(sig)
}
/// Creates a new var
fn create_var(&mut self, builder: &mut FunctionBuilder, ty: Type) -> Result<Variable> {
let id = self.vars.len();
let var = Variable::new(id);
builder.declare_var(var, ty);
self.vars.push((ty, var));
Ok(var)
}
fn vars_of_type(&self, ty: Type) -> Vec<Variable> {
self.vars
.iter()
.filter(|(var_ty, _)| *var_ty == ty)
.map(|(_, v)| *v)
.collect()
}
/// Get a variable of type `ty` from the current function
fn get_variable_of_type(&mut self, ty: Type) -> Result<Variable> {
let opts = self.vars_of_type(ty);
let var = self.u.choose(&opts[..])?;
Ok(*var)
}
/// Generates an instruction(`iconst`/`fconst`/etc...) to introduce a constant value
fn generate_const(&mut self, builder: &mut FunctionBuilder, ty: Type) -> Result<Value> {
let imm64 = match ty {
I8 => self.u.arbitrary::<i8>()? as i64,
I16 => self.u.arbitrary::<i16>()? as i64,
I32 => self.u.arbitrary::<i32>()? as i64,
I64 => self.u.arbitrary::<i64>()?,
_ => unreachable!(),
};
let val = builder.ins().iconst(ty, imm64);
Ok(val)
}
fn generate_return(&mut self, builder: &mut FunctionBuilder) -> Result<()> {
let ret_params = builder.func.signature.returns.clone();
let vars = ret_params
.iter()
.map(|p| self.get_variable_of_type(p.value_type))
.collect::<Result<Vec<_>>>()?;
let vals = vars
.into_iter()
.map(|v| builder.use_var(v))
.collect::<Vec<_>>();
builder.ins().return_(&vals[..]);
Ok(())
}
/// Inserts a random instruction into the block
fn generate_instruction(&mut self, builder: &mut FunctionBuilder) -> Result<()> {
let (op, args, rets, inserter) = *self.u.choose(OPCODE_SIGNATURES)?;
inserter(self, builder, op, args, rets)
}
pub fn generate(mut self) -> Result<Function> {
let sig = self.generate_signature()?;
let mut fn_builder_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig.clone());
let mut builder = FunctionBuilder::new(&mut func, &mut fn_builder_ctx);
let block0 = builder.create_block();
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
builder.seal_block(block0);
// Define variables for the function signature
for (i, param) in sig.params.iter().enumerate() {
let var = self.create_var(&mut builder, param.value_type)?;
let block_param = builder.block_params(block0)[i];
builder.def_var(var, block_param);
}
// Create a pool of vars that are going to be used in this function
for _ in 0..self.u.int_in_range(self.config.vars_per_function.clone())? {
let ty = self.generate_type()?;
let var = self.create_var(&mut builder, ty)?;
let value = self.generate_const(&mut builder, ty)?;
builder.def_var(var, value);
}
for _ in 0..self
.u
.int_in_range(self.config.instructions_per_block.clone())?
{
self.generate_instruction(&mut builder)?;
}
// TODO: We should make this part of the regular instruction selection
self.generate_return(&mut builder)?;
builder.finalize();
Ok(func)
}
}

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use crate::config::Config;
use crate::function_generator::FunctionGenerator;
use anyhow::Result;
use arbitrary::{Arbitrary, Unstructured};
use cranelift::codegen::data_value::DataValue;
use cranelift::codegen::ir::types::*;
use cranelift::codegen::ir::Function;
use cranelift::prelude::*;
mod config;
mod function_generator;
pub type TestCaseInput = Vec<DataValue>;
#[derive(Debug)]
pub struct TestCase {
pub func: Function,
/// Generate multiple test inputs for each test case.
/// This allows us to get more coverage per compilation, which may be somewhat expensive.
pub inputs: Vec<TestCaseInput>,
}
impl<'a> Arbitrary<'a> for TestCase {
fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
FuzzGen::new(u)
.generate_test()
.map_err(|_| arbitrary::Error::IncorrectFormat)
}
}
pub struct FuzzGen<'r, 'data>
where
'data: 'r,
{
u: &'r mut Unstructured<'data>,
config: Config,
}
impl<'r, 'data> FuzzGen<'r, 'data>
where
'data: 'r,
{
pub fn new(u: &'r mut Unstructured<'data>) -> Self {
Self {
u,
config: Config::default(),
}
}
fn generate_test_inputs(&mut self, signature: &Signature) -> Result<Vec<TestCaseInput>> {
let num_tests = self.u.int_in_range(self.config.test_case_inputs.clone())?;
let mut inputs = Vec::with_capacity(num_tests);
for _ in 0..num_tests {
let test_args = signature
.params
.iter()
.map(|p| {
let imm64 = match p.value_type {
I8 => self.u.arbitrary::<i8>()? as i64,
I16 => self.u.arbitrary::<i16>()? as i64,
I32 => self.u.arbitrary::<i32>()? as i64,
I64 => self.u.arbitrary::<i64>()?,
_ => unreachable!(),
};
Ok(DataValue::from_integer(imm64, p.value_type)?)
})
.collect::<Result<TestCaseInput>>()?;
inputs.push(test_args);
}
Ok(inputs)
}
pub fn generate_test(mut self) -> Result<TestCase> {
let func = FunctionGenerator::new(&mut self.u, &self.config).generate()?;
let inputs = self.generate_test_inputs(&func.signature)?;
Ok(TestCase { func, inputs })
}
}

2
cranelift/interpreter/src/step.rs
View File

@@ -664,7 +664,7 @@ impl<'a, V> ControlFlow<'a, V> {
}
}
#[derive(Error, Debug)]
#[derive(Error, Debug, PartialEq)]
pub enum CraneliftTrap {
#[error("user code: {0}")]
User(TrapCode),

15
fuzz/Cargo.toml
View File

@@ -12,6 +12,9 @@ cargo-fuzz = true
cranelift-codegen = { path = "../cranelift/codegen" }
cranelift-reader = { path = "../cranelift/reader" }
cranelift-wasm = { path = "../cranelift/wasm" }
cranelift-filetests = { path = "../cranelift/filetests" }
cranelift-interpreter = { path = "../cranelift/interpreter" }
cranelift-fuzzgen = { path = "../cranelift/fuzzgen" }
libfuzzer-sys = "0.4.0"
target-lexicon = "0.12"
peepmatic-fuzzing = { path = "../cranelift/peepmatic/crates/fuzzing", optional = true }
@@ -84,3 +87,15 @@ name = "instantiate-maybe-invalid"
path = "fuzz_targets/instantiate-maybe-invalid.rs"
test = false
doc = false
[[bin]]
name = "cranelift-fuzzgen"
path = "fuzz_targets/cranelift-fuzzgen.rs"
test = false
doc = false
[[bin]]
name = "cranelift-fuzzgen-verify"
path = "fuzz_targets/cranelift-fuzzgen-verify.rs"
test = false
doc = false

11
fuzz/fuzz_targets/cranelift-fuzzgen-verify.rs Normal file
View File

@@ -0,0 +1,11 @@
#![no_main]
use libfuzzer_sys::fuzz_target;
use cranelift_codegen::{settings, verify_function};
use cranelift_fuzzgen::TestCase;
fuzz_target!(|testcase: TestCase| {
let flags = settings::Flags::new(settings::builder());
verify_function(&testcase.func, &flags).unwrap();
});

85
fuzz/fuzz_targets/cranelift-fuzzgen.rs Normal file
View File

@@ -0,0 +1,85 @@
#![no_main]
use libfuzzer_sys::fuzz_target;
use cranelift_codegen::data_value::DataValue;
use cranelift_filetests::function_runner::{CompiledFunction, SingleFunctionCompiler};
use cranelift_fuzzgen::*;
use cranelift_interpreter::environment::FuncIndex;
use cranelift_interpreter::environment::FunctionStore;
use cranelift_interpreter::interpreter::{Interpreter, InterpreterState};
use cranelift_interpreter::step::ControlFlow;
use cranelift_interpreter::step::CraneliftTrap;
#[derive(Debug)]
enum RunResult {
Success(Vec<DataValue>),
Trap(CraneliftTrap),
Error(Box<dyn std::error::Error>),
}
impl RunResult {
pub fn unwrap(self) -> Vec<DataValue> {
match self {
RunResult::Success(d) => d,
_ => panic!("Expected RunResult::Success in unwrap but got: {:?}", self),
}
}
}
fn run_in_interpreter(interpreter: &mut Interpreter, args: &[DataValue]) -> RunResult {
// The entrypoint function is always 0
let index = FuncIndex::from_u32(0);
let res = interpreter.call_by_index(index, args);
match res {
Ok(ControlFlow::Return(results)) => RunResult::Success(results.to_vec()),
Ok(ControlFlow::Trap(trap)) => RunResult::Trap(trap),
Ok(cf) => RunResult::Error(format!("Unrecognized exit ControlFlow: {:?}", cf).into()),
Err(e) => RunResult::Error(format!("InterpreterError: {:?}", e).into()),
}
}
fn run_in_host(compiled_fn: &CompiledFunction, args: &[DataValue]) -> RunResult {
let res = compiled_fn.call(args);
RunResult::Success(res)
}
fuzz_target!(|testcase: TestCase| {
let mut interpreter = {
let mut env = FunctionStore::default();
env.add(testcase.func.name.to_string(), &testcase.func);
let state = InterpreterState::default().with_function_store(env);
let interpreter = Interpreter::new(state);
interpreter
};
// Native fn
let mut host_compiler = SingleFunctionCompiler::with_default_host_isa();
let compiled_fn = host_compiler.compile(testcase.func.clone()).unwrap();
for args in &testcase.inputs {
let int_res = run_in_interpreter(&mut interpreter, args);
match int_res {
RunResult::Success(_) => {}
RunResult::Trap(_) => {
// We currently ignore inputs that trap the interpreter
// We could catch traps in the host run and compare them to the
// interpreter traps, but since we already test trap cases with
// wasm tests and wasm-level fuzzing, the amount of effort does
// not justify implementing it again here.
return;
}
RunResult::Error(_) => panic!("interpreter failed: {:?}", int_res),
}
let host_res = run_in_host(&compiled_fn, args);
match host_res {
RunResult::Success(_) => {}
_ => panic!("host failed: {:?}", host_res),
}
assert_eq!(int_res.unwrap(), host_res.unwrap());
}
});