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Uplift clippy::invalid_null_ptr_usage as invalid_null_arguments 
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5 files changed

+461
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‎compiler/rustc_lint/messages.ftl‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -456,6 +456,10 @@ lint_invalid_nan_comparisons_eq_ne = incorrect NaN comparison, NaN cannot be dir
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457457
lint_invalid_nan_comparisons_lt_le_gt_ge = incorrect NaN comparison, NaN is not orderable
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459+
lint_invalid_null_arguments = calling this function with a null pointer is Undefined Behavior, even if the result of the function is unused
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.note = null pointer originate from here
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.suggestion = consider using a dangling pointer instead
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459463
lint_invalid_reference_casting_assign_to_ref = assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
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.label = casting happened here
461465

‎compiler/rustc_lint/src/lints.rs‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -609,6 +609,30 @@ pub(crate) enum UselessPtrNullChecksDiag<'a> {
609609
FnRet { fn_name: Ident },
610610
}
611611

612+
#[derive(LintDiagnostic)]
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#[diag(lint_invalid_null_arguments)]
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pub(crate) struct InvalidNullArgumentsDiag<'a> {
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#[note]
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pub null_span: Option<Span>,
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#[subdiagnostic]
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pub suggestion: InvalidNullArgumentsSuggestion<'a>,
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}
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621+
#[derive(Subdiagnostic)]
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pub(crate) enum InvalidNullArgumentsSuggestion<'a> {
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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WithoutExplicitType {
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#[suggestion_part(code = "core::ptr::NonNull::dangling().as_ptr()")]
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arg_span: Span,
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},
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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WithExplicitType {
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ty: Ty<'a>,
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#[suggestion_part(code = "core::ptr::NonNull::<{ty}>::dangling().as_ptr()")]
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arg_span: Span,
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},
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}
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612636
// for_loops_over_fallibles.rs
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#[derive(LintDiagnostic)]
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#[diag(lint_for_loops_over_fallibles)]

‎compiler/rustc_lint/src/ptr_nulls.rs‎

Lines changed: 104 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,13 @@
11
use rustc_ast::LitKind;
22
use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind};
3+
use rustc_middle::ty::RawPtr;
34
use rustc_session::{declare_lint, declare_lint_pass};
4-
use rustc_span::sym;
5+
use rustc_span::{Span, sym};
56

6-
use crate::lints::UselessPtrNullChecksDiag;
7+
use crate::lints::{
8+
InvalidNullArgumentsDiag, InvalidNullArgumentsSuggestion, UselessPtrNullChecksDiag,
9+
};
10+
use crate::utils::peel_casts;
711
use crate::{LateContext, LateLintPass, LintContext};
812

913
declare_lint! {
@@ -31,7 +35,30 @@ declare_lint! {
3135
"useless checking of non-null-typed pointer"
3236
}
3337

34-
declare_lint_pass!(PtrNullChecks => [USELESS_PTR_NULL_CHECKS]);
38+
declare_lint! {
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/// The `invalid_null_arguments` lint checks for invalid usage of null pointers in arguments.
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///
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/// ### Example
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///
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/// ```rust,compile_fail
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/// # use std::{slice, ptr};
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/// // Undefined behavior
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/// # let _slice: &[u8] =
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/// unsafe { slice::from_raw_parts(ptr::null(), 0) };
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/// ```
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///
50+
/// {{produces}}
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///
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/// ### Explanation
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///
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/// Calling methods whos safety invariants requires non-null ptr with a null pointer
55+
/// is Undefined Behavior!
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INVALID_NULL_ARGUMENTS,
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Deny,
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"invalid null pointer in arguments"
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}
60+
61+
declare_lint_pass!(PtrNullChecks => [USELESS_PTR_NULL_CHECKS, INVALID_NULL_ARGUMENTS]);
3562

3663
/// This function checks if the expression is from a series of consecutive casts,
3764
/// ie. `(my_fn as *const _ as *mut _).cast_mut()` and whether the original expression is either
@@ -85,6 +112,25 @@ fn useless_check<'a, 'tcx: 'a>(
85112
}
86113
}
87114

115+
/// Checks if the given expression is a null pointer (modulo casting)
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fn is_null_ptr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Span> {
117+
let (expr, _) = peel_casts(cx, expr);
118+
119+
if let ExprKind::Call(path, []) = expr.kind
120+
&& let ExprKind::Path(ref qpath) = path.kind
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&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
122+
&& let Some(diag_item) = cx.tcx.get_diagnostic_name(def_id)
123+
{
124+
(diag_item == sym::ptr_null || diag_item == sym::ptr_null_mut).then_some(expr.span)
125+
} else if let ExprKind::Lit(spanned) = expr.kind
126+
&& let LitKind::Int(v, _) = spanned.node
127+
{
128+
(v == 0).then_some(expr.span)
129+
} else {
130+
None
131+
}
132+
}
133+
88134
impl<'tcx> LateLintPass<'tcx> for PtrNullChecks {
89135
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
90136
match expr.kind {
@@ -102,6 +148,61 @@ impl<'tcx> LateLintPass<'tcx> for PtrNullChecks {
102148
cx.emit_span_lint(USELESS_PTR_NULL_CHECKS, expr.span, diag)
103149
}
104150

151+
// Catching:
152+
// <path>(arg...) where `arg` is null-ptr and `path` is a fn that expect non-null-ptr
153+
ExprKind::Call(path, args)
154+
if let ExprKind::Path(ref qpath) = path.kind
155+
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
156+
&& let Some(diag_name) = cx.tcx.get_diagnostic_name(def_id) =>
157+
{
158+
// `arg` positions where null would cause U.B.
159+
//
160+
// We should probably have a `rustc` attribute, but checking them is costly,
161+
// maybe if we checked for null ptr first, it would be acceptable?
162+
let arg_indices: &[_] = match diag_name {
163+
sym::ptr_read
164+
| sym::ptr_read_unaligned
165+
| sym::ptr_read_volatile
166+
| sym::ptr_replace
167+
| sym::ptr_write
168+
| sym::ptr_write_bytes
169+
| sym::ptr_write_unaligned
170+
| sym::ptr_write_volatile
171+
| sym::slice_from_raw_parts
172+
| sym::slice_from_raw_parts_mut => &[0],
173+
sym::ptr_copy
174+
| sym::ptr_copy_nonoverlapping
175+
| sym::ptr_swap
176+
| sym::ptr_swap_nonoverlapping => &[0, 1],
177+
_ => return,
178+
};
179+
180+
for &arg_idx in arg_indices {
181+
if let Some(arg) = args.get(arg_idx)
182+
&& let Some(null_span) = is_null_ptr(cx, arg)
183+
{
184+
let arg_span = arg.span;
185+
186+
let suggestion = if let ExprKind::Cast(..) = arg.peel_blocks().kind
187+
&& let Some(ty) = cx.typeck_results().expr_ty_opt(arg)
188+
&& let RawPtr(ty, _mutbl) = ty.kind()
189+
{
190+
InvalidNullArgumentsSuggestion::WithExplicitType { ty: *ty, arg_span }
191+
} else {
192+
InvalidNullArgumentsSuggestion::WithoutExplicitType { arg_span }
193+
};
194+
195+
let null_span = if arg_span != null_span { Some(null_span) } else { None };
196+
197+
cx.emit_span_lint(
198+
INVALID_NULL_ARGUMENTS,
199+
expr.span,
200+
InvalidNullArgumentsDiag { null_span, suggestion },
201+
)
202+
}
203+
}
204+
}
205+
105206
// Catching:
106207
// (fn_ptr as *<const/mut> <ty>).is_null()
107208
ExprKind::MethodCall(_, receiver, _, _)

‎tests/ui/lint/invalid_null_args.rs‎

Lines changed: 101 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,101 @@
1+
// check-fail
2+
// run-rustfix
3+
4+
use std::ptr;
5+
use std::mem;
6+
7+
unsafe fn null_ptr() {
8+
ptr::write(
9+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
10+
ptr::null_mut() as *mut u32,
11+
mem::transmute::<[u8; 4], _>([0, 0, 0, 255]),
12+
);
13+
14+
let _: &[usize] = std::slice::from_raw_parts(ptr::null(), 0);
15+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
16+
let _: &[usize] = std::slice::from_raw_parts(ptr::null_mut(), 0);
17+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
18+
let _: &[usize] = std::slice::from_raw_parts(0 as *mut _, 0);
19+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
20+
let _: &[usize] = std::slice::from_raw_parts(mem::transmute(0usize), 0);
21+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
22+
23+
let _: &[usize] = std::slice::from_raw_parts_mut(ptr::null_mut(), 0);
24+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
25+
26+
ptr::copy::<usize>(ptr::null(), ptr::NonNull::dangling().as_ptr(), 0);
27+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
28+
ptr::copy::<usize>(ptr::NonNull::dangling().as_ptr(), ptr::null_mut(), 0);
29+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
30+
31+
ptr::copy_nonoverlapping::<usize>(ptr::null(), ptr::NonNull::dangling().as_ptr(), 0);
32+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
33+
ptr::copy_nonoverlapping::<usize>(
34+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
35+
ptr::NonNull::dangling().as_ptr(),
36+
ptr::null_mut(),
37+
0
38+
);
39+
40+
struct A; // zero sized struct
41+
assert_eq!(std::mem::size_of::<A>(), 0);
42+
43+
let _a: A = ptr::read(ptr::null());
44+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
45+
let _a: A = ptr::read(ptr::null_mut());
46+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
47+
48+
let _a: A = ptr::read_unaligned(ptr::null());
49+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
50+
let _a: A = ptr::read_unaligned(ptr::null_mut());
51+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
52+
53+
let _a: A = ptr::read_volatile(ptr::null());
54+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
55+
let _a: A = ptr::read_volatile(ptr::null_mut());
56+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
57+
58+
let _a: A = ptr::replace(ptr::null_mut(), A);
59+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
60+
61+
ptr::swap::<A>(ptr::null_mut(), &mut A);
62+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
63+
ptr::swap::<A>(&mut A, ptr::null_mut());
64+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
65+
66+
ptr::swap_nonoverlapping::<A>(ptr::null_mut(), &mut A, 0);
67+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
68+
ptr::swap_nonoverlapping::<A>(&mut A, ptr::null_mut(), 0);
69+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
70+
71+
ptr::write(ptr::null_mut(), A);
72+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
73+
74+
ptr::write_unaligned(ptr::null_mut(), A);
75+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
76+
77+
ptr::write_volatile(ptr::null_mut(), A);
78+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
79+
80+
ptr::write_bytes::<usize>(ptr::null_mut(), 42, 0);
81+
//~^ ERROR calling this function with a null pointer is Undefined Behavior
82+
}
83+
84+
unsafe fn not_invalid() {
85+
// Simplified false-positive from std quicksort implementation
86+
87+
let mut a = ptr::null_mut();
88+
let mut b = ();
89+
90+
loop {
91+
if false {
92+
break;
93+
}
94+
95+
a = &raw mut b;
96+
}
97+
98+
ptr::write(a, ());
99+
}
100+
101+
fn main() {}

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