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Merged
merged 2 commits into from
Nov 14, 2022
Merged

Address issues with rustc 1.65 #31

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2d44ec6
As of rustc 1.65, Vec/Layout size > isize::MAX is UB
glandium Nov 4, 2022
f26cad6
Don't allow allocation sizes larger than isize::MAX in vec_try_extend
glandium Nov 4, 2022
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13 changes: 11 additions & 2 deletions src/vec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -472,6 +472,7 @@ fn vec_try_extend<T>(v: &mut Vec<T>, new_cap: usize) -> Result<(), TryReserveErr
let elem_size = core::mem::size_of::<T>();
let new_alloc_size = new_cap
.checked_mul(elem_size)
.filter(|size| *size <= isize::MAX as usize)
.ok_or(TryReserveError::CapacityOverflow)?;

// required for alloc safety
Expand Down Expand Up @@ -824,15 +825,15 @@ mod tests {
fn try_clone_oom() {
let layout = Layout::new::<u8>();
let v =
unsafe { Vec::<u8>::from_raw_parts(alloc(layout), core::usize::MAX, core::usize::MAX) };
unsafe { Vec::<u8>::from_raw_parts(alloc(layout), core::isize::MAX as usize, core::isize::MAX as usize) };
assert!(v.try_clone().is_err());
}

#[test]
fn tryvec_try_clone_oom() {
let layout = Layout::new::<u8>();
let inner =
unsafe { Vec::<u8>::from_raw_parts(alloc(layout), core::usize::MAX, core::usize::MAX) };
unsafe { Vec::<u8>::from_raw_parts(alloc(layout), core::isize::MAX as usize, core::isize::MAX as usize) };
let tv = TryVec { inner };
assert!(tv.try_clone().is_err());
}
Expand All @@ -846,6 +847,10 @@ mod tests {
#[test]
fn oom() {
let mut vec: Vec<char> = Vec::new();
match FallibleVec::try_reserve(&mut vec, core::usize::MAX / std::mem::size_of::<char>()) {
Ok(_) => panic!("it should be OOM"),
_ => (),
}
Comment on lines +850 to +853
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I recognize this matches the existing code, but it strikes me as odd to use a match here rather than a simple assert like

Suggested change
match FallibleVec::try_reserve(&mut vec, core::usize::MAX / std::mem::size_of::<char>()) {
Ok(_) => panic!("it should be OOM"),
_ => (),
}
assert!(FallibleVec::try_reserve(&mut vec, core::usize::MAX / std::mem::size_of::<char>()).is_err());

For the sake of clarity, it seems worth changing both to the more idiomatic approach.

Also, based on https://rust-lang.github.io/unsafe-code-guidelines/layout/scalars.html#isize-and-usize, should this be testing the tighter bound of isize::MAX?

match FallibleVec::try_reserve(&mut vec, core::usize::MAX) {
Ok(_) => panic!("it should be OOM"),
_ => (),
Expand All @@ -855,6 +860,10 @@ mod tests {
#[test]
fn tryvec_oom() {
let mut vec: TryVec<char> = TryVec::new();
match vec.reserve(core::usize::MAX / std::mem::size_of::<char>()) {
Ok(_) => panic!("it should be OOM"),
_ => (),
}
match vec.reserve(core::usize::MAX) {
Ok(_) => panic!("it should be OOM"),
_ => (),
Expand Down