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Merged
merged 6 commits into from May 5, 2020
Merged

Check that shims are called with the correct number of arguments #1298

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78f3295
Check that shims are called with the correct number of arguments
npcmp Apr 2, 2020
46aaab3
Add a test for check_arg_count.
npcmp Apr 30, 2020
4d3dff2
Address consistency of naming for unused/merely validated arguments.
npcmp Apr 30, 2020
f46d197
Test for too many args.
npcmp Apr 30, 2020
4e3d1fe
Address comments.
npcmp May 4, 2020
f741f2c
Correct the test.
npcmp May 5, 2020
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11 changes: 10 additions & 1 deletion src/helpers.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
use std::convert::TryFrom;
use std::convert::{TryFrom, TryInto};
use std::mem;
use std::num::NonZeroUsize;

Expand Down Expand Up @@ -471,6 +471,15 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
}
}

/// Check that the number of args is what we expect.
pub fn check_arg_count<'a, 'tcx, const N: usize>(args: &'a [OpTy<'tcx, Tag>]) -> InterpResult<'tcx, &'a [OpTy<'tcx, Tag>; N]>
where &'a [OpTy<'tcx, Tag>; N]: TryFrom<&'a [OpTy<'tcx, Tag>]> {
if let Ok(ops) = args.try_into() {
return Ok(ops);
}
throw_ub_format!("incorrect number of arguments: got {}, expected {}", args.len(), N)
}

pub fn immty_from_int_checked<'tcx>(
int: impl Into<i128>,
layout: TyAndLayout<'tcx>,
Expand Down
3 changes: 3 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,9 @@
#![warn(rust_2018_idioms)]
#![allow(clippy::cast_lossless)]

#![allow(incomplete_features)]
#![feature(const_generics)]

extern crate rustc_apfloat;
extern crate rustc_ast;
#[macro_use] extern crate rustc_middle;
Expand Down
6 changes: 4 additions & 2 deletions src/shims/dlsym.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use rustc_middle::mir;

use crate::*;
use helpers::check_arg_count;

#[derive(Debug, Copy, Clone)]
pub enum Dlsym {
Expand Down Expand Up @@ -35,8 +36,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx

match dlsym {
GetEntropy => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
let &[ptr, len] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
let len = this.read_scalar(len)?.to_machine_usize(this)?;
this.gen_random(ptr, len)?;
this.write_null(dest)?;
}
Expand Down
92 changes: 56 additions & 36 deletions src/shims/foreign_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use rustc_span::symbol::sym;
use rustc_ast::attr;

use crate::*;
use helpers::check_arg_count;

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
Expand Down Expand Up @@ -139,8 +140,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "exit"
| "ExitProcess"
=> {
let &[code] = check_arg_count(args)?;
// it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
let code = this.read_scalar(args[0])?.to_i32()?;
let code = this.read_scalar(code)?.to_i32()?;
throw_machine_stop!(TerminationInfo::Exit(code.into()));
}
_ => throw_unsup_format!("can't call (diverging) foreign function: {}", link_name),
Expand Down Expand Up @@ -197,25 +199,29 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
match link_name {
// Standard C allocation
"malloc" => {
let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
let &[size] = check_arg_count(args)?;
let size = this.read_scalar(size)?.to_machine_usize(this)?;
let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
this.write_scalar(res, dest)?;
}
"calloc" => {
let items = this.read_scalar(args[0])?.to_machine_usize(this)?;
let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
let &[items, len] = check_arg_count(args)?;
let items = this.read_scalar(items)?.to_machine_usize(this)?;
let len = this.read_scalar(len)?.to_machine_usize(this)?;
let size =
items.checked_mul(len).ok_or_else(|| err_ub_format!("overflow during calloc size computation"))?;
let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
this.write_scalar(res, dest)?;
}
"free" => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let &[ptr] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
this.free(ptr, MiriMemoryKind::C)?;
}
"realloc" => {
let old_ptr = this.read_scalar(args[0])?.not_undef()?;
let new_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
let &[old_ptr, new_size] = check_arg_count(args)?;
let old_ptr = this.read_scalar(old_ptr)?.not_undef()?;
let new_size = this.read_scalar(new_size)?.to_machine_usize(this)?;
let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
this.write_scalar(res, dest)?;
}
Expand All @@ -224,8 +230,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
// (Usually these would be forwarded to to `#[global_allocator]`; we instead implement a generic
// allocation that also checks that all conditions are met, such as not permitting zero-sized allocations.)
"__rust_alloc" => {
let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
let &[size, align] = check_arg_count(args)?;
let size = this.read_scalar(size)?.to_machine_usize(this)?;
let align = this.read_scalar(align)?.to_machine_usize(this)?;
Self::check_alloc_request(size, align)?;
let ptr = this.memory.allocate(
Size::from_bytes(size),
Expand All @@ -235,8 +242,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.write_scalar(ptr, dest)?;
}
"__rust_alloc_zeroed" => {
let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
let &[size, align] = check_arg_count(args)?;
let size = this.read_scalar(size)?.to_machine_usize(this)?;
let align = this.read_scalar(align)?.to_machine_usize(this)?;
Self::check_alloc_request(size, align)?;
let ptr = this.memory.allocate(
Size::from_bytes(size),
Expand All @@ -248,9 +256,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.write_scalar(ptr, dest)?;
}
"__rust_dealloc" => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
let &[ptr, old_size, align] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
let old_size = this.read_scalar(old_size)?.to_machine_usize(this)?;
let align = this.read_scalar(align)?.to_machine_usize(this)?;
// No need to check old_size/align; we anyway check that they match the allocation.
let ptr = this.force_ptr(ptr)?;
this.memory.deallocate(
Expand All @@ -260,12 +269,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
)?;
}
"__rust_realloc" => {
let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
let new_size = this.read_scalar(args[3])?.to_machine_usize(this)?;
let &[ptr, old_size, align, new_size] = check_arg_count(args)?;
let ptr = this.force_ptr(this.read_scalar(ptr)?.not_undef()?)?;
let old_size = this.read_scalar(old_size)?.to_machine_usize(this)?;
let align = this.read_scalar(align)?.to_machine_usize(this)?;
let new_size = this.read_scalar(new_size)?.to_machine_usize(this)?;
Self::check_alloc_request(new_size, align)?;
// No need to check old_size; we anyway check that they match the allocation.
let ptr = this.force_ptr(this.read_scalar(args[0])?.not_undef()?)?;
let align = Align::from_bytes(align).unwrap();
let new_ptr = this.memory.reallocate(
ptr,
Expand All @@ -279,9 +289,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx

// C memory handling functions
"memcmp" => {
let left = this.read_scalar(args[0])?.not_undef()?;
let right = this.read_scalar(args[1])?.not_undef()?;
let n = Size::from_bytes(this.read_scalar(args[2])?.to_machine_usize(this)?);
let &[left, right, n] = check_arg_count(args)?;
let left = this.read_scalar(left)?.not_undef()?;
let right = this.read_scalar(right)?.not_undef()?;
let n = Size::from_bytes(this.read_scalar(n)?.to_machine_usize(this)?);

let result = {
let left_bytes = this.memory.read_bytes(left, n)?;
Expand All @@ -298,9 +309,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.write_scalar(Scalar::from_i32(result), dest)?;
}
"memrchr" => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let val = this.read_scalar(args[1])?.to_i32()? as u8;
let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
let &[ptr, val, num] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
let val = this.read_scalar(val)?.to_i32()? as u8;
let num = this.read_scalar(num)?.to_machine_usize(this)?;
if let Some(idx) = this
.memory
.read_bytes(ptr, Size::from_bytes(num))?
Expand All @@ -315,9 +327,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
}
}
"memchr" => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let val = this.read_scalar(args[1])?.to_i32()? as u8;
let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
let &[ptr, val, num] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
let val = this.read_scalar(val)?.to_i32()? as u8;
let num = this.read_scalar(num)?.to_machine_usize(this)?;
let idx = this
.memory
.read_bytes(ptr, Size::from_bytes(num))?
Expand All @@ -331,7 +344,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
}
}
"strlen" => {
let ptr = this.read_scalar(args[0])?.not_undef()?;
let &[ptr] = check_arg_count(args)?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
let n = this.memory.read_c_str(ptr)?.len();
this.write_scalar(Scalar::from_machine_usize(u64::try_from(n).unwrap(), this), dest)?;
}
Expand All @@ -345,8 +359,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "asinf"
| "atanf"
=> {
let &[f] = check_arg_count(args)?;
// FIXME: Using host floats.
let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
let f = f32::from_bits(this.read_scalar(f)?.to_u32()?);
let f = match link_name {
"cbrtf" => f.cbrt(),
"coshf" => f.cosh(),
Expand All @@ -363,11 +378,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "hypotf"
| "atan2f"
=> {
let &[f1, f2] = check_arg_count(args)?;
// underscore case for windows, here and below
// (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
// FIXME: Using host floats.
let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
let f1 = f32::from_bits(this.read_scalar(f1)?.to_u32()?);
let f2 = f32::from_bits(this.read_scalar(f2)?.to_u32()?);
let n = match link_name {
"_hypotf" | "hypotf" => f1.hypot(f2),
"atan2f" => f1.atan2(f2),
Expand All @@ -383,8 +399,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "asin"
| "atan"
=> {
let &[f] = check_arg_count(args)?;
// FIXME: Using host floats.
let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
let f = f64::from_bits(this.read_scalar(f)?.to_u64()?);
let f = match link_name {
"cbrt" => f.cbrt(),
"cosh" => f.cosh(),
Expand All @@ -401,9 +418,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "hypot"
| "atan2"
=> {
let &[f1, f2] = check_arg_count(args)?;
// FIXME: Using host floats.
let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
let f1 = f64::from_bits(this.read_scalar(f1)?.to_u64()?);
let f2 = f64::from_bits(this.read_scalar(f2)?.to_u64()?);
let n = match link_name {
"_hypot" | "hypot" => f1.hypot(f2),
"atan2" => f1.atan2(f2),
Expand All @@ -415,9 +433,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
| "ldexp"
| "scalbn"
=> {
let &[x, exp] = check_arg_count(args)?;
// For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
let x = this.read_scalar(args[0])?.to_f64()?;
let exp = this.read_scalar(args[1])?.to_i32()?;
let x = this.read_scalar(x)?.to_f64()?;
let exp = this.read_scalar(exp)?.to_i32()?;

// Saturating cast to i16. Even those are outside the valid exponent range to
// `scalbn` below will do its over/underflow handling.
Expand All @@ -435,6 +454,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx

// Architecture-specific shims
"llvm.x86.sse2.pause" if this.tcx.sess.target.target.arch == "x86" || this.tcx.sess.target.target.arch == "x86_64" => {
let &[] = check_arg_count(args)?;
this.sched_yield()?;
}

Expand Down
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