Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Validation: check raw wide pointer metadata #63880

Merged
merged 5 commits into from
Aug 29, 2019
Merged

Validation: check raw wide pointer metadata #63880

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
92e75c0
factor wide ptr metadata checking into separate method
RalfJung Aug 25, 2019
96baf1c
validate raw wide pointers
RalfJung Aug 25, 2019
0c1cb32
test for too long slices
RalfJung Aug 25, 2019
ae78862
raw slices do not have to comply to the size limit
RalfJung Aug 26, 2019
04580b6
adjust tests
RalfJung Aug 26, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
100 changes: 64 additions & 36 deletions src/librustc_mir/interpret/validity.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,15 @@ use std::ops::RangeInclusive;

use syntax_pos::symbol::{sym, Symbol};
use rustc::hir;
use rustc::ty::layout::{self, TyLayout, LayoutOf, VariantIdx};
use rustc::ty::layout::{self, Size, TyLayout, LayoutOf, VariantIdx};
use rustc::ty;
use rustc_data_structures::fx::FxHashSet;

use std::hash::Hash;

use super::{
GlobalAlloc, InterpResult,
OpTy, Machine, InterpCx, ValueVisitor, MPlaceTy,
Scalar, OpTy, Machine, InterpCx, ValueVisitor, MPlaceTy,
};

macro_rules! throw_validation_failure {
Expand Down Expand Up @@ -250,6 +250,56 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M
self.path.truncate(path_len);
Ok(())
}

fn check_wide_ptr_meta(
&mut self,
meta: Option<Scalar<M::PointerTag>>,
pointee: TyLayout<'tcx>,
) -> InterpResult<'tcx> {
let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
match tail.sty {
ty::Dynamic(..) => {
let vtable = meta.unwrap();
try_validation!(
self.ecx.memory.check_ptr_access(
vtable,
3*self.ecx.tcx.data_layout.pointer_size, // drop, size, align
self.ecx.tcx.data_layout.pointer_align.abi,
),
"dangling or unaligned vtable pointer in wide pointer or too small vtable",
self.path
);
try_validation!(self.ecx.read_drop_type_from_vtable(vtable),
"invalid drop fn in vtable", self.path);
try_validation!(self.ecx.read_size_and_align_from_vtable(vtable),
"invalid size or align in vtable", self.path);
// FIXME: More checks for the vtable.
}
ty::Slice(..) | ty::Str => {
let len = try_validation!(meta.unwrap().to_usize(self.ecx),
"non-integer slice length in wide pointer", self.path);
// check max slice length
let elem_size = match tail.sty {
ty::Str => Size::from_bytes(1),
ty::Slice(ty) => self.ecx.layout_of(ty)?.size,
_ => bug!("It cannot be another type"),
};
if elem_size.checked_mul(len, &*self.ecx.tcx).is_none() {
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

(offtopic) @oli-obk why doesn't TyCtxtAt just implement the right traits to not require all of these &* in miri?

throw_validation_failure!(
"too large slice (longer than isize::MAX bytes)",
self.path
);
}
}
ty::Foreign(..) => {
// Unsized, but not wide.
}
_ =>
bug!("Unexpected unsized type tail: {:?}", tail),
}

Ok(())
}
}

impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
Expand Down Expand Up @@ -341,56 +391,34 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
}
}
ty::RawPtr(..) => {
// Check pointer part.
if self.ref_tracking_for_consts.is_some() {
// Integers/floats in CTFE: For consistency with integers, we do not
// accept undef.
let _ptr = try_validation!(value.to_scalar_ptr(),
"undefined address in raw pointer", self.path);
let _meta = try_validation!(value.to_meta(),
"uninitialized data in raw fat pointer metadata", self.path);
} else {
// Remain consistent with `usize`: Accept anything.
}

// Check metadata.
let meta = try_validation!(value.to_meta(),
"uninitialized data in wide pointer metadata", self.path);
let layout = self.ecx.layout_of(value.layout.ty.builtin_deref(true).unwrap().ty)?;
if layout.is_unsized() {
self.check_wide_ptr_meta(meta, layout)?;
}
}
_ if ty.is_box() || ty.is_region_ptr() => {
// Handle fat pointers.
// Handle wide pointers.
// Check metadata early, for better diagnostics
let ptr = try_validation!(value.to_scalar_ptr(),
"undefined address in pointer", self.path);
let meta = try_validation!(value.to_meta(),
"uninitialized data in fat pointer metadata", self.path);
"uninitialized data in wide pointer metadata", self.path);
let layout = self.ecx.layout_of(value.layout.ty.builtin_deref(true).unwrap().ty)?;
if layout.is_unsized() {
let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(layout.ty,
self.ecx.param_env);
match tail.sty {
ty::Dynamic(..) => {
let vtable = meta.unwrap();
try_validation!(
self.ecx.memory.check_ptr_access(
vtable,
3*self.ecx.tcx.data_layout.pointer_size, // drop, size, align
self.ecx.tcx.data_layout.pointer_align.abi,
),
"dangling or unaligned vtable pointer or too small vtable",
self.path
);
try_validation!(self.ecx.read_drop_type_from_vtable(vtable),
"invalid drop fn in vtable", self.path);
try_validation!(self.ecx.read_size_and_align_from_vtable(vtable),
"invalid size or align in vtable", self.path);
// FIXME: More checks for the vtable.
}
ty::Slice(..) | ty::Str => {
try_validation!(meta.unwrap().to_usize(self.ecx),
"non-integer slice length in fat pointer", self.path);
}
ty::Foreign(..) => {
// Unsized, but not fat.
}
_ =>
bug!("Unexpected unsized type tail: {:?}", tail),
}
self.check_wide_ptr_meta(meta, layout)?;
}
// Make sure this is dereferencable and all.
let (size, align) = self.ecx.size_and_align_of(meta, layout)?
Expand Down
74 changes: 50 additions & 24 deletions .../ui/consts/const-eval/union-ub-fat-ptr.rs → src/test/ui/consts/const-eval/ub-wide-ptr.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
// ignore-tidy-linelength
#![allow(unused)]
#![allow(const_err)] // make sure we cannot allow away the errors tested here

Expand Down Expand Up @@ -28,7 +29,9 @@ struct BadSliceRepr {
union SliceTransmute {
repr: SliceRepr,
bad: BadSliceRepr,
addr: usize,
slice: &'static [u8],
raw_slice: *const [u8],
str: &'static str,
my_str: &'static MyStr,
my_slice: &'static MySliceBool,
Expand Down Expand Up @@ -59,7 +62,9 @@ union DynTransmute {
repr: DynRepr,
repr2: DynRepr2,
bad: BadDynRepr,
addr: usize,
rust: &'static dyn Trait,
raw_rust: *const dyn Trait,
}

trait Trait {}
Expand All @@ -72,39 +77,37 @@ struct MyStr(str);
struct MySlice<T: ?Sized>(bool, T);
type MySliceBool = MySlice<[bool]>;

// # str
// OK
const A: &str = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 1 } }.str};
const STR_VALID: &str = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 1 } }.str};
// bad str
const B: &str = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 999 } }.str};
const STR_TOO_LONG: &str = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 999 } }.str};
//~^ ERROR it is undefined behavior to use this value
// bad str
const C: &str = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.str};
const STR_LENGTH_PTR: &str = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.str};
//~^ ERROR it is undefined behavior to use this value
// bad str in user-defined unsized type
const C2: &MyStr = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.my_str};
const MY_STR_LENGTH_PTR: &MyStr = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.my_str};
//~^ ERROR it is undefined behavior to use this value

// OK
const A2: &[u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 1 } }.slice};
// bad slice
const B2: &[u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 999 } }.slice};
// invalid UTF-8
const J1: &str = unsafe { SliceTransmute { slice: &[0xFF] }.str };
//~^ ERROR it is undefined behavior to use this value
// bad slice
const C3: &[u8] = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.slice};
// invalid UTF-8 in user-defined str-like
const J2: &MyStr = unsafe { SliceTransmute { slice: &[0xFF] }.my_str };
//~^ ERROR it is undefined behavior to use this value

// bad trait object
const D: &dyn Trait = unsafe { DynTransmute { repr: DynRepr { ptr: &92, vtable: &3 } }.rust};
//~^ ERROR it is undefined behavior to use this value
// bad trait object
const E: &dyn Trait = unsafe { DynTransmute { repr2: DynRepr2 { ptr: &92, vtable: &3 } }.rust};
// # slice
// OK
const SLICE_VALID: &[u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 1 } }.slice};
// bad slice: length uninit
const SLICE_LENGTH_UNINIT: &[u8] = unsafe { SliceTransmute { addr: 42 }.slice};
//~^ ERROR it is undefined behavior to use this value
// bad trait object
const F: &dyn Trait = unsafe { DynTransmute { bad: BadDynRepr { ptr: &92, vtable: 3 } }.rust};
// bad slice: length too big
const SLICE_TOO_LONG: &[u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 999 } }.slice};
//~^ ERROR it is undefined behavior to use this value

// bad data *inside* the trait object
const G: &dyn Trait = &unsafe { BoolTransmute { val: 3 }.bl };
// bad slice: length not an int
const SLICE_LENGTH_PTR: &[u8] = unsafe { SliceTransmute { bad: BadSliceRepr { ptr: &42, len: &3 } }.slice};
//~^ ERROR it is undefined behavior to use this value

// bad data *inside* the slice
Expand All @@ -120,12 +123,35 @@ const I2: &MySliceBool = &MySlice(unsafe { BoolTransmute { val: 3 }.bl }, [false
const I3: &MySliceBool = &MySlice(true, [unsafe { BoolTransmute { val: 3 }.bl }]);
//~^ ERROR it is undefined behavior to use this value

// invalid UTF-8
const J1: &str = unsafe { SliceTransmute { slice: &[0xFF] }.str };
// # raw slice
const RAW_SLICE_VALID: *const [u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 1 } }.raw_slice}; // ok
const RAW_SLICE_TOO_LONG: *const [u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: 999 } }.raw_slice}; // ok because raw
const RAW_SLICE_MUCH_TOO_LONG: *const [u8] = unsafe { SliceTransmute { repr: SliceRepr { ptr: &42, len: usize::max_value() } }.raw_slice};
//~^ ERROR it is undefined behavior to use this value
// invalid UTF-8 in user-defined str-like
const J2: &MyStr = unsafe { SliceTransmute { slice: &[0xFF] }.my_str };
const RAW_SLICE_LENGTH_UNINIT: *const [u8] = unsafe { SliceTransmute { addr: 42 }.raw_slice};
//~^ ERROR it is undefined behavior to use this value

// # trait object
// bad trait object
const D: &dyn Trait = unsafe { DynTransmute { repr: DynRepr { ptr: &92, vtable: &3 } }.rust};
//~^ ERROR it is undefined behavior to use this value
// bad trait object
const E: &dyn Trait = unsafe { DynTransmute { repr2: DynRepr2 { ptr: &92, vtable: &3 } }.rust};
//~^ ERROR it is undefined behavior to use this value
// bad trait object
const F: &dyn Trait = unsafe { DynTransmute { bad: BadDynRepr { ptr: &92, vtable: 3 } }.rust};
//~^ ERROR it is undefined behavior to use this value

// bad data *inside* the trait object
const G: &dyn Trait = &unsafe { BoolTransmute { val: 3 }.bl };
//~^ ERROR it is undefined behavior to use this value

// # raw trait object
const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { DynTransmute { bad: BadDynRepr { ptr: &92, vtable: 0 } }.rust};
//~^ ERROR it is undefined behavior to use this value
const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { DynTransmute { repr2: DynRepr2 { ptr: &92, vtable: &3 } }.raw_rust};
//~^ ERROR it is undefined behavior to use this value
const RAW_TRAIT_OBJ_CONTENT_INVALID: *const dyn Trait = &unsafe { BoolTransmute { val: 3 }.bl } as *const _; // ok because raw

fn main() {
}
Loading