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[Draft] Combine multiple range checks to handle noncontiguous ranges #3362

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[Draft] Combine multiple range checks to handle noncontiguous ranges #3362

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d78604a
Check two ranges for `char` values
adpaco-aws Jul 15, 2024
a99fdb3
Generate combined checks for ranges
adpaco-aws Jul 19, 2024
85886da
Merge branch 'main' into check-char-surrogate
adpaco-aws Jul 19, 2024
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148 changes: 95 additions & 53 deletions kani-compiler/src/kani_middle/transform/check_values.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,34 +87,32 @@ impl ValidValuePass {
SourceOp::BytesValidity { ranges, target_ty, rvalue } => {
let value = body.new_assignment(rvalue, &mut source, InsertPosition::Before);
let rvalue_ptr = Rvalue::AddressOf(Mutability::Not, Place::from(value));
for range in ranges {
let result = build_limits(body, &range, rvalue_ptr.clone(), &mut source);
let msg =
format!("Undefined Behavior: Invalid value of type `{target_ty}`",);
body.add_check(
tcx,
&self.check_type,
&mut source,
InsertPosition::Before,
result,
&msg,
);
}
// for range in ranges {
let result = build_limits(body, &ranges, rvalue_ptr.clone(), &mut source);
let msg = format!("Undefined Behavior: Invalid value of type `{target_ty}`",);
body.add_check(
tcx,
&self.check_type,
&mut source,
InsertPosition::Before,
result,
&msg,
);
// }
}
SourceOp::DerefValidity { pointee_ty, rvalue, ranges } => {
for range in ranges {
let result = build_limits(body, &range, rvalue.clone(), &mut source);
let msg =
format!("Undefined Behavior: Invalid value of type `{pointee_ty}`",);
body.add_check(
tcx,
&self.check_type,
&mut source,
InsertPosition::Before,
result,
&msg,
);
}
// for range in ranges {
let result = build_limits(body, &ranges, rvalue.clone(), &mut source);
let msg = format!("Undefined Behavior: Invalid value of type `{pointee_ty}`",);
body.add_check(
tcx,
&self.check_type,
&mut source,
InsertPosition::Before,
result,
&msg,
);
// }
}
SourceOp::UnsupportedCheck { check, ty } => {
let reason = format!(
Expand Down Expand Up @@ -764,16 +762,14 @@ fn expect_instance(locals: &[LocalDecl], func: &Operand) -> Instance {
/// ```
pub fn build_limits(
body: &mut MutableBody,
req: &ValidValueReq,
reqs: &Vec<ValidValueReq>,
rvalue_ptr: Rvalue,
source: &mut SourceInstruction,
) -> Local {
let span = source.span(body.blocks());
debug!(?req, ?rvalue_ptr, ?span, "build_limits");
let primitive_ty = uint_ty(req.size.bytes());
let start_const = body.new_const_operand(req.valid_range.start, primitive_ty, span);
let end_const = body.new_const_operand(req.valid_range.end, primitive_ty, span);
let orig_ptr = if req.offset != 0 {
debug!(?reqs, ?rvalue_ptr, ?span, "build_limits");
let primitive_ty = uint_ty(reqs[0].size.bytes());
let orig_ptr = if reqs[0].offset != 0 {
let start_ptr = move_local(body.new_assignment(rvalue_ptr, source, InsertPosition::Before));
let byte_ptr = move_local(body.new_cast_ptr(
start_ptr,
Expand All @@ -782,7 +778,7 @@ pub fn build_limits(
source,
InsertPosition::Before,
));
let offset_const = body.new_const_operand(req.offset as _, UintTy::Usize, span);
let offset_const = body.new_const_operand(reqs[0].offset as _, UintTy::Usize, span);
let offset = move_local(body.new_assignment(
Rvalue::Use(offset_const),
source,
Expand All @@ -806,29 +802,52 @@ pub fn build_limits(
InsertPosition::Before,
);
let value = Operand::Copy(Place { local: value_ptr, projection: vec![ProjectionElem::Deref] });
let start_result =
body.new_binary_op(BinOp::Ge, value.clone(), start_const, source, InsertPosition::Before);
let end_result =
body.new_binary_op(BinOp::Le, value, end_const, source, InsertPosition::Before);
if req.valid_range.wraps_around() {
// valid >= start || valid <= end
body.new_binary_op(
BinOp::BitOr,
move_local(start_result),
move_local(end_result),
source,
InsertPosition::Before,
)
} else {
// valid >= start && valid <= end
body.new_binary_op(
BinOp::BitAnd,
move_local(start_result),
move_local(end_result),
let mut prev_local = None;
for req in reqs {
let start_const = body.new_const_operand(req.valid_range.start, primitive_ty, span);
let end_const = body.new_const_operand(req.valid_range.end, primitive_ty, span);
let start_result = body.new_binary_op(
BinOp::Ge,
value.clone(),
start_const,
source,
InsertPosition::Before,
)
);
let end_result =
body.new_binary_op(BinOp::Le, value.clone(), end_const, source, InsertPosition::Before);
let range_check = if req.valid_range.wraps_around() {
// valid >= start || valid <= end
body.new_binary_op(
BinOp::BitOr,
move_local(start_result),
move_local(end_result),
source,
InsertPosition::Before,
)
} else {
// valid >= start && valid <= end
body.new_binary_op(
BinOp::BitAnd,
move_local(start_result),
move_local(end_result),
source,
InsertPosition::Before,
)
};
if prev_local.is_none() {
prev_local = Some(range_check);
} else {
let record_local = prev_local.unwrap();
prev_local = Some(body.new_binary_op(
BinOp::BitOr,
move_local(record_local),
move_local(range_check),
source,
InsertPosition::Before,
));
};
}
prev_local.unwrap()
}

/// Traverse the type and find all invalid values and their location in memory.
Expand All @@ -839,8 +858,31 @@ pub fn ty_validity_per_offset(
ty: Ty,
current_offset: usize,
) -> Result<Vec<ValidValueReq>, String> {
debug!(typ=?ty, kind=?ty.kind(), "ty_validity_per_offset");
let layout = ty.layout().unwrap().shape();
let ty_req = || {
if ty.kind() == TyKind::RigidTy(RigidTy::Char) {
let shape = ty.layout().unwrap().shape();
let value_size = match shape.abi {
ValueAbi::Scalar(Scalar::Initialized { value, .. })
| ValueAbi::ScalarPair(Scalar::Initialized { value, .. }, _) => {
Some(value.size(machine_info))
}
_ => None,
};
return vec![
ValidValueReq {
offset: 0,
size: value_size.unwrap(),
valid_range: WrappingRange { start: 0, end: 0xD7FF },
},
ValidValueReq {
offset: 0,
size: value_size.unwrap(),
valid_range: WrappingRange { start: 0xE000, end: 0x10FFFF },
},
];
};
if let Some(mut req) = ValidValueReq::try_from_ty(machine_info, ty)
&& !req.is_full()
{
Expand Down
23 changes: 11 additions & 12 deletions kani-compiler/src/kani_middle/transform/kani_intrinsics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,18 +115,17 @@ impl IntrinsicGeneratorPass {
Ok(ranges) => {
// Given the pointer argument, check for possible invalid ranges.
let rvalue = Rvalue::Use(Operand::Move(Place::from(1)));
for range in ranges {
let result =
build_limits(&mut new_body, &range, rvalue.clone(), &mut terminator);
let rvalue = Rvalue::BinaryOp(
BinOp::BitAnd,
Operand::Move(Place::from(ret_var)),
Operand::Move(Place::from(result)),
);
let assign = StatementKind::Assign(Place::from(ret_var), rvalue);
let stmt = Statement { kind: assign, span };
new_body.insert_stmt(stmt, &mut terminator, InsertPosition::Before);
}
// for range in &ranges {
let result = build_limits(&mut new_body, &ranges, rvalue.clone(), &mut terminator);
let rvalue = Rvalue::BinaryOp(
BinOp::BitAnd,
Operand::Move(Place::from(ret_var)),
Operand::Move(Place::from(result)),
);
let assign = StatementKind::Assign(Place::from(ret_var), rvalue);
let stmt = Statement { kind: assign, span };
new_body.insert_stmt(stmt, &mut terminator, InsertPosition::Before);
// }
}
Err(msg) => {
// We failed to retrieve all the valid ranges.
Expand Down
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