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Auto merge of #4592 - rust-lang:transmute-collection, r=flip1995

Browse source 
New lint: `unsound_collection_transmute`

changelog: Add `unsound_collection_transmute` lint

This fixes #4515
This commit is contained in:
bors 2019-10-08 05:51:07 +00:00
commit e2393b09ac
9 changed files with 491 additions and 258 deletions
Download patch file Download diff file Expand all files Collapse all files

2
clippy_lints/src/lib.rs
View file

@ -893,6 +893,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
transmute::TRANSMUTE_INT_TO_FLOAT,
transmute::TRANSMUTE_PTR_TO_PTR,
transmute::TRANSMUTE_PTR_TO_REF,
transmute::UNSOUND_COLLECTION_TRANSMUTE,
transmute::USELESS_TRANSMUTE,
transmute::WRONG_TRANSMUTE,
transmuting_null::TRANSMUTING_NULL,
@ -1148,6 +1149,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL,
suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL,
swap::ALMOST_SWAPPED,
transmute::UNSOUND_COLLECTION_TRANSMUTE,
transmute::WRONG_TRANSMUTE,
transmuting_null::TRANSMUTING_NULL,
types::ABSURD_EXTREME_COMPARISONS,

532
clippy_lints/src/transmute.rs
View file

@ -216,6 +216,33 @@ declare_clippy_lint! {
"transmutes from a pointer to a pointer / a reference to a reference"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes between collections whose
/// types have different ABI, size or alignment.
///
/// **Why is this bad?** This is undefined behavior.
///
/// **Known problems:** Currently, we cannot know whether a type is a
/// collection, so we just lint the ones that come with `std`.
///
/// **Example:**
/// ```rust
/// // different size, therefore likely out-of-bounds memory access
/// // You absolutely do not want this in your code!
/// unsafe {
/// std::mem::transmute::<_, Vec<u32>>(vec![2_u16])
/// };
/// ```
///
/// You must always iterate, map and collect the values:
///
/// ```rust
/// vec![2_u16].into_iter().map(u32::from).collect::<Vec<_>>();
/// ```
pub UNSOUND_COLLECTION_TRANSMUTE,
correctness,
"transmute between collections of layout-incompatible types"
}
declare_lint_pass!(Transmute => [
CROSSPOINTER_TRANSMUTE,
TRANSMUTE_PTR_TO_REF,
@ -226,262 +253,292 @@ declare_lint_pass!(Transmute => [
TRANSMUTE_BYTES_TO_STR,
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
UNSOUND_COLLECTION_TRANSMUTE,
]);
// used to check for UNSOUND_COLLECTION_TRANSMUTE
static COLLECTIONS: &[&[&str]] = &[
&paths::VEC,
&paths::VEC_DEQUE,
&paths::BINARY_HEAP,
&paths::BTREESET,
&paths::BTREEMAP,
&paths::HASHSET,
&paths::HASHMAP,
];
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Transmute {
#[allow(clippy::similar_names, clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
if let ExprKind::Call(ref path_expr, ref args) = e.kind {
if let ExprKind::Path(ref qpath) = path_expr.kind {
if let Some(def_id) = cx.tables.qpath_res(qpath, path_expr.hir_id).opt_def_id() {
if match_def_path(cx, def_id, &paths::TRANSMUTE) {
let from_ty = cx.tables.expr_ty(&args[0]);
let to_ty = cx.tables.expr_ty(e);
if_chain! {
if let ExprKind::Call(ref path_expr, ref args) = e.kind;
if let ExprKind::Path(ref qpath) = path_expr.kind;
if let Some(def_id) = cx.tables.qpath_res(qpath, path_expr.hir_id).opt_def_id();
if match_def_path(cx, def_id, &paths::TRANSMUTE);
then {
let from_ty = cx.tables.expr_ty(&args[0]);
let to_ty = cx.tables.expr_ty(e);
match (&from_ty.kind, &to_ty.kind) {
_ if from_ty == to_ty => span_lint(
cx,
USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty),
),
(&ty::Ref(_, rty, rty_mutbl), &ty::RawPtr(ptr_ty)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from a reference to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let rty_and_mut = ty::TypeAndMut {
ty: rty,
mutbl: rty_mutbl,
};
match (&from_ty.kind, &to_ty.kind) {
_ if from_ty == to_ty => span_lint(
cx,
USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty),
),
(&ty::Ref(_, rty, rty_mutbl), &ty::RawPtr(ptr_ty)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from a reference to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let rty_and_mut = ty::TypeAndMut {
ty: rty,
mutbl: rty_mutbl,
};
let sugg = if ptr_ty == rty_and_mut {
arg.as_ty(to_ty)
} else {
arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
};
let sugg = if ptr_ty == rty_and_mut {
arg.as_ty(to_ty)
} else {
arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
};
db.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(&ty::Int(_), &ty::RawPtr(_)) | (&ty::Uint(_), &ty::RawPtr(_)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from an integer to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
db.span_suggestion(
e.span,
"try",
arg.as_ty(&to_ty.to_string()).to_string(),
Applicability::Unspecified,
);
}
},
),
(&ty::Float(_), &ty::Ref(..))
| (&ty::Float(_), &ty::RawPtr(_))
| (&ty::Char, &ty::Ref(..))
| (&ty::Char, &ty::RawPtr(_)) => span_lint(
cx,
WRONG_TRANSMUTE,
e.span,
&format!("transmute from a `{}` to a pointer", from_ty),
),
(&ty::RawPtr(from_ptr), _) if from_ptr.ty == to_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to the type that it points to (`{}`)",
from_ty, to_ty
),
),
(_, &ty::RawPtr(to_ptr)) if to_ptr.ty == from_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to a pointer to that type (`{}`)",
from_ty, to_ty
),
),
(&ty::RawPtr(from_pty), &ty::Ref(_, to_ref_ty, mutbl)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_REF,
e.span,
&format!(
"transmute from a pointer type (`{}`) to a reference type \
(`{}`)",
from_ty, to_ty
),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let (deref, cast) = if mutbl == Mutability::MutMutable {
("&mut *", "*mut")
} else {
("&*", "*const")
};
db.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(&ty::Int(_), &ty::RawPtr(_)) | (&ty::Uint(_), &ty::RawPtr(_)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from an integer to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
db.span_suggestion(
e.span,
"try",
arg.as_ty(&to_ty.to_string()).to_string(),
Applicability::Unspecified,
);
}
},
),
(&ty::Float(_), &ty::Ref(..))
| (&ty::Float(_), &ty::RawPtr(_))
| (&ty::Char, &ty::Ref(..))
| (&ty::Char, &ty::RawPtr(_)) => span_lint(
cx,
WRONG_TRANSMUTE,
e.span,
&format!("transmute from a `{}` to a pointer", from_ty),
),
(&ty::RawPtr(from_ptr), _) if from_ptr.ty == to_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to the type that it points to (`{}`)",
from_ty, to_ty
),
),
(_, &ty::RawPtr(to_ptr)) if to_ptr.ty == from_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to a pointer to that type (`{}`)",
from_ty, to_ty
),
),
(&ty::RawPtr(from_pty), &ty::Ref(_, to_ref_ty, mutbl)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_REF,
e.span,
&format!(
"transmute from a pointer type (`{}`) to a reference type \
(`{}`)",
from_ty, to_ty
),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let (deref, cast) = if mutbl == Mutability::MutMutable {
("&mut *", "*mut")
} else {
("&*", "*const")
};
let arg = if from_pty.ty == to_ref_ty {
arg
} else {
arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
};
let arg = if from_pty.ty == to_ref_ty {
arg
} else {
arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
};
db.span_suggestion(
e.span,
"try",
sugg::make_unop(deref, arg).to_string(),
Applicability::Unspecified,
);
},
),
(&ty::Int(ast::IntTy::I32), &ty::Char) | (&ty::Uint(ast::UintTy::U32), &ty::Char) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_CHAR,
e.span,
&format!("transmute from a `{}` to a `char`", from_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(_) = from_ty.kind {
arg.as_ty(ast::UintTy::U32)
} else {
arg
};
db.span_suggestion(
e.span,
"consider using",
format!("std::char::from_u32({}).unwrap()", arg.to_string()),
Applicability::Unspecified,
);
},
)
},
(&ty::Ref(_, ty_from, from_mutbl), &ty::Ref(_, ty_to, to_mutbl)) => {
if_chain! {
if let (&ty::Slice(slice_ty), &ty::Str) = (&ty_from.kind, &ty_to.kind);
if let ty::Uint(ast::UintTy::U8) = slice_ty.kind;
if from_mutbl == to_mutbl;
then {
let postfix = if from_mutbl == Mutability::MutMutable {
"_mut"
} else {
""
};
db.span_suggestion(
e.span,
"try",
sugg::make_unop(deref, arg).to_string(),
Applicability::Unspecified,
);
},
),
(&ty::Int(ast::IntTy::I32), &ty::Char) | (&ty::Uint(ast::UintTy::U32), &ty::Char) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_CHAR,
TRANSMUTE_BYTES_TO_STR,
e.span,
&format!("transmute from a `{}` to a `char`", from_ty),
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(_) = from_ty.kind {
arg.as_ty(ast::UintTy::U32)
} else {
arg
};
db.span_suggestion(
e.span,
"consider using",
format!("std::char::from_u32({}).unwrap()", arg.to_string()),
format!(
"std::str::from_utf8{}({}).unwrap()",
postfix,
snippet(cx, args[0].span, ".."),
),
Applicability::Unspecified,
);
},
}
)
},
(&ty::Ref(_, ty_from, from_mutbl), &ty::Ref(_, ty_to, to_mutbl)) => {
if_chain! {
if let (&ty::Slice(slice_ty), &ty::Str) = (&ty_from.kind, &ty_to.kind);
if let ty::Uint(ast::UintTy::U8) = slice_ty.kind;
if from_mutbl == to_mutbl;
then {
let postfix = if from_mutbl == Mutability::MutMutable {
"_mut"
} else {
""
};
span_lint_and_then(
cx,
TRANSMUTE_BYTES_TO_STR,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|db| {
db.span_suggestion(
e.span,
"consider using",
format!(
"std::str::from_utf8{}({}).unwrap()",
postfix,
snippet(cx, args[0].span, ".."),
),
Applicability::Unspecified,
);
}
)
} else {
if cx.tcx.erase_regions(&from_ty) != cx.tcx.erase_regions(&to_ty) {
span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
} else {
if cx.tcx.erase_regions(&from_ty) != cx.tcx.erase_regions(&to_ty) {
span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a reference to a reference",
|db| if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let ty_from_and_mut = ty::TypeAndMut {
ty: ty_from,
mutbl: from_mutbl
};
let ty_to_and_mut = ty::TypeAndMut { ty: ty_to, mutbl: to_mutbl };
let sugg_paren = arg
.as_ty(cx.tcx.mk_ptr(ty_from_and_mut))
.as_ty(cx.tcx.mk_ptr(ty_to_and_mut));
let sugg = if to_mutbl == Mutability::MutMutable {
sugg_paren.mut_addr_deref()
} else {
sugg_paren.addr_deref()
};
db.span_suggestion(
e.span,
"transmute from a reference to a reference",
|db| if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let ty_from_and_mut = ty::TypeAndMut {
ty: ty_from,
mutbl: from_mutbl
};
let ty_to_and_mut = ty::TypeAndMut { ty: ty_to, mutbl: to_mutbl };
let sugg_paren = arg
.as_ty(cx.tcx.mk_ptr(ty_from_and_mut))
.as_ty(cx.tcx.mk_ptr(ty_to_and_mut));
let sugg = if to_mutbl == Mutability::MutMutable {
sugg_paren.mut_addr_deref()
} else {
sugg_paren.addr_deref()
};
db.span_suggestion(
e.span,
"try",
sugg.to_string(),
Applicability::Unspecified,
);
},
)
}
}
"try",
sugg.to_string(),
Applicability::Unspecified,
);
},
)
}
},
(&ty::RawPtr(_), &ty::RawPtr(to_ty)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a pointer to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let sugg = arg.as_ty(cx.tcx.mk_ptr(to_ty));
db.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(&ty::Int(ast::IntTy::I8), &ty::Bool) | (&ty::Uint(ast::UintTy::U8), &ty::Bool) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_BOOL,
}
}
},
(&ty::RawPtr(_), &ty::RawPtr(to_ty)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a pointer to a pointer",
|db| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let sugg = arg.as_ty(cx.tcx.mk_ptr(to_ty));
db.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(&ty::Int(ast::IntTy::I8), &ty::Bool) | (&ty::Uint(ast::UintTy::U8), &ty::Bool) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_BOOL,
e.span,
&format!("transmute from a `{}` to a `bool`", from_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let zero = sugg::Sugg::NonParen(Cow::from("0"));
db.span_suggestion(
e.span,
&format!("transmute from a `{}` to a `bool`", from_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let zero = sugg::Sugg::NonParen(Cow::from("0"));
db.span_suggestion(
e.span,
"consider using",
sugg::make_binop(ast::BinOpKind::Ne, &arg, &zero).to_string(),
Applicability::Unspecified,
);
},
)
"consider using",
sugg::make_binop(ast::BinOpKind::Ne, &arg, &zero).to_string(),
Applicability::Unspecified,
);
},
(&ty::Int(_), &ty::Float(_)) | (&ty::Uint(_), &ty::Float(_)) => span_lint_and_then(
cx,
TRANSMUTE_INT_TO_FLOAT,
)
},
(&ty::Int(_), &ty::Float(_)) | (&ty::Uint(_), &ty::Float(_)) => span_lint_and_then(
cx,
TRANSMUTE_INT_TO_FLOAT,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(int_ty) = from_ty.kind {
arg.as_ty(format!(
"u{}",
int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
))
} else {
arg
};
db.span_suggestion(
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|db| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(int_ty) = from_ty.kind {
arg.as_ty(format!(
"u{}",
int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
))
} else {
arg
};
db.span_suggestion(
e.span,
"consider using",
format!("{}::from_bits({})", to_ty, arg.to_string()),
Applicability::Unspecified,
);
},
),
_ => return,
};
}
"consider using",
format!("{}::from_bits({})", to_ty, arg.to_string()),
Applicability::Unspecified,
);
},
),
(&ty::Adt(ref from_adt, ref from_substs), &ty::Adt(ref to_adt, ref to_substs)) => {
if from_adt.did != to_adt.did ||
!COLLECTIONS.iter().any(|path| match_def_path(cx, to_adt.did, path)) {
return;
}
if from_substs.types().zip(to_substs.types())
.any(|(from_ty, to_ty)| is_layout_incompatible(cx, from_ty, to_ty)) {
span_lint(
cx,
UNSOUND_COLLECTION_TRANSMUTE,
e.span,
&format!(
"transmute from `{}` to `{}` with mismatched layout is unsound",
from_ty,
to_ty
)
);
}
},
_ => return,
}
}
}
@ -510,3 +567,16 @@ fn get_type_snippet(cx: &LateContext<'_, '_>, path: &QPath, to_ref_ty: Ty<'_>) -
to_ref_ty.to_string()
}
// check if the component types of the transmuted collection and the result have different ABI,
// size or alignment
fn is_layout_incompatible<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, from: Ty<'tcx>, to: Ty<'tcx>) -> bool {
let from_ty_layout = cx.tcx.layout_of(ty::ParamEnv::empty().and(from));
let to_ty_layout = cx.tcx.layout_of(ty::ParamEnv::empty().and(to));
if let (Ok(from_layout), Ok(to_layout)) = (from_ty_layout, to_ty_layout) {
from_layout.size != to_layout.size || from_layout.align != to_layout.align || from_layout.abi != to_layout.abi
} else {
// no idea about layout, so don't lint
false
}
}