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Be more careful about integer overflow when computing relocs.

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This commit is contained in:
Dan Gohman
2018-11-29 10:28:18 -08:00
parent f7dc961d2c
commit b7d43edfd3
2 changed files with 21 additions and 18 deletions
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6
lib/environ/src/environ.rs
View File

@@ -122,8 +122,8 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
real_call_args
}
fn pointer_bytes(&self) -> usize {
usize::from(self.isa.pointer_bytes())
fn pointer_bytes(&self) -> u8 {
self.isa.pointer_bytes()
}
fn vmctx(&mut self, func: &mut Function) -> ir::GlobalValue {
@@ -405,7 +405,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
base_gv,
min_size: Imm64::new(0),
bound_gv,
element_size: Imm64::new(i64::from(self.pointer_bytes() as i64)),
element_size: Imm64::new(i64::from(self.pointer_bytes())),
index_type: I32,
})
}

33
lib/execute/src/execute.rs
View File

@@ -24,7 +24,7 @@ pub fn compile_and_link_module<'data, 'module, F>(
imports: F,
) -> Result<Compilation, String>
where
F: Fn(&str, &str) -> Option<isize>,
F: Fn(&str, &str) -> Option<usize>,
{
let (mut compilation, relocations) = compile_module(&translation, isa)?;
@@ -41,15 +41,15 @@ fn relocate<F>(
module: &Module,
imports: F,
) where
F: Fn(&str, &str) -> Option<isize>,
F: Fn(&str, &str) -> Option<usize>,
{
// The relocations are relative to the relocation's address plus four bytes
// TODO: Support architectures other than x64, and other reloc kinds.
for (i, function_relocs) in relocations.iter() {
for r in function_relocs {
let target_func_address: isize = match r.reloc_target {
let target_func_address: usize = match r.reloc_target {
RelocationTarget::UserFunc(index) => match module.defined_func_index(index) {
Some(f) => compilation.functions[f].as_ptr() as isize,
Some(f) => compilation.functions[f].as_ptr() as usize,
None => {
let func = &module.imported_funcs[index.index()];
match imports(&func.0, &func.1) {
@@ -60,25 +60,28 @@ fn relocate<F>(
}
}
},
RelocationTarget::GrowMemory => grow_memory as isize,
RelocationTarget::CurrentMemory => current_memory as isize,
RelocationTarget::GrowMemory => grow_memory as usize,
RelocationTarget::CurrentMemory => current_memory as usize,
};
let body = &mut compilation.functions[i];
match r.reloc {
Reloc::Abs8 => unsafe {
let reloc_address = body.as_mut_ptr().offset(r.offset as isize) as i64;
let reloc_addend = r.addend;
let reloc_abs = target_func_address as i64 + reloc_addend;
write_unaligned(reloc_address as *mut i64, reloc_abs);
let reloc_address = body.as_mut_ptr().add(r.offset as usize) as usize;
let reloc_addend = r.addend as isize;
let reloc_abs = (target_func_address as u64)
.checked_add(reloc_addend as u64)
.unwrap();
write_unaligned(reloc_address as *mut u64, reloc_abs);
},
Reloc::X86PCRel4 => unsafe {
let reloc_address = body.as_mut_ptr().offset(r.offset as isize) as isize;
let reloc_address = body.as_mut_ptr().add(r.offset as usize) as usize;
let reloc_addend = r.addend as isize;
// TODO: Handle overflow.
let reloc_delta_i32 =
(target_func_address - reloc_address + reloc_addend) as i32;
write_unaligned(reloc_address as *mut i32, reloc_delta_i32);
let reloc_delta_u32 = (target_func_address as u32)
.wrapping_sub(reloc_address as u32)
.checked_add(reloc_addend as u32)
.unwrap();
write_unaligned(reloc_address as *mut u32, reloc_delta_u32);
},
_ => panic!("unsupported reloc kind"),
}