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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 real_call_args
} }
fn pointer_bytes(&self) -> usize { fn pointer_bytes(&self) -> u8 {
usize::from(self.isa.pointer_bytes()) self.isa.pointer_bytes()
} }
fn vmctx(&mut self, func: &mut Function) -> ir::GlobalValue { fn vmctx(&mut self, func: &mut Function) -> ir::GlobalValue {
@@ -405,7 +405,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
base_gv, base_gv,
min_size: Imm64::new(0), min_size: Imm64::new(0),
bound_gv, 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, 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, imports: F,
) -> Result<Compilation, String> ) -> Result<Compilation, String>
where where
F: Fn(&str, &str) -> Option<isize>, F: Fn(&str, &str) -> Option<usize>,
{ {
let (mut compilation, relocations) = compile_module(&translation, isa)?; let (mut compilation, relocations) = compile_module(&translation, isa)?;
@@ -41,15 +41,15 @@ fn relocate<F>(
module: &Module, module: &Module,
imports: F, imports: F,
) where ) 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 // The relocations are relative to the relocation's address plus four bytes
// TODO: Support architectures other than x64, and other reloc kinds. // TODO: Support architectures other than x64, and other reloc kinds.
for (i, function_relocs) in relocations.iter() { for (i, function_relocs) in relocations.iter() {
for r in function_relocs { 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) { 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 => { None => {
let func = &module.imported_funcs[index.index()]; let func = &module.imported_funcs[index.index()];
match imports(&func.0, &func.1) { match imports(&func.0, &func.1) {
@@ -60,25 +60,28 @@ fn relocate<F>(
} }
} }
}, },
RelocationTarget::GrowMemory => grow_memory as isize, RelocationTarget::GrowMemory => grow_memory as usize,
RelocationTarget::CurrentMemory => current_memory as isize, RelocationTarget::CurrentMemory => current_memory as usize,
}; };
let body = &mut compilation.functions[i]; let body = &mut compilation.functions[i];
match r.reloc { match r.reloc {
Reloc::Abs8 => unsafe { Reloc::Abs8 => unsafe {
let reloc_address = body.as_mut_ptr().offset(r.offset as isize) as i64; let reloc_address = body.as_mut_ptr().add(r.offset as usize) as usize;
let reloc_addend = r.addend; let reloc_addend = r.addend as isize;
let reloc_abs = target_func_address as i64 + reloc_addend; let reloc_abs = (target_func_address as u64)
write_unaligned(reloc_address as *mut i64, reloc_abs); .checked_add(reloc_addend as u64)
.unwrap();
write_unaligned(reloc_address as *mut u64, reloc_abs);
}, },
Reloc::X86PCRel4 => unsafe { 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; let reloc_addend = r.addend as isize;
// TODO: Handle overflow. let reloc_delta_u32 = (target_func_address as u32)
let reloc_delta_i32 = .wrapping_sub(reloc_address as u32)
(target_func_address - reloc_address + reloc_addend) as i32; .checked_add(reloc_addend as u32)
write_unaligned(reloc_address as *mut i32, reloc_delta_i32); .unwrap();
write_unaligned(reloc_address as *mut u32, reloc_delta_u32);
}, },
_ => panic!("unsupported reloc kind"), _ => panic!("unsupported reloc kind"),
} }