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alloc: remove unsound IsZero for raw pointers

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Fixes #135338
This commit is contained in:
joboet 2025-01-10 18:48:48 +01:00
parent 336209eef1
commit 4426e9a3c2
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GPG key ID: 704E0149B0194B3C
2 changed files with 12 additions and 13 deletions
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15
library/alloc/src/vec/is_zero.rs
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@ -40,19 +40,8 @@ impl_is_zero!(char, |x| x == '\0');
impl_is_zero!(f32, |x: f32| x.to_bits() == 0);
impl_is_zero!(f64, |x: f64| x.to_bits() == 0);
unsafe impl<T> IsZero for *const T {
#[inline]
fn is_zero(&self) -> bool {
(*self).is_null()
}
}
unsafe impl<T> IsZero for *mut T {
#[inline]
fn is_zero(&self) -> bool {
(*self).is_null()
}
}
// `IsZero` cannot be soundly implemented for pointers because of provenance
// (see #135338).
unsafe impl<T: IsZero, const N: usize> IsZero for [T; N] {
#[inline]

10
library/alloc/tests/vec.rs
View file

@ -2742,3 +2742,13 @@ fn max_swap_remove() {
let mut v = vec![0];
v.swap_remove(usize::MAX);
}
// Regression test for #135338
#[test]
fn vec_null_ptr_roundtrip() {
let ptr = std::ptr::from_ref(&42);
let zero = ptr.with_addr(0);
let roundtripped = vec![zero; 1].pop().unwrap();
let new = roundtripped.with_addr(ptr.addr());
unsafe { new.read() };
}