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rust: alloc: Fix ArrayLayout allocations

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We were accidentally allocating a layout for the *square* of the object
size due to a variable shadowing mishap.

Fixes memory bloat and page allocation failures in drm/asahi.

Reported-by: Janne Grunau <j@jannau.net>
Fixes: 9e7bbfa182 ("rust: alloc: introduce `ArrayLayout`")
Signed-off-by: Asahi Lina <lina@asahilina.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Link: https://lore.kernel.org/r/20241123-rust-fix-arraylayout-v1-1-197e64c95bd4@asahilina.net
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Asahi Lina 2024-11-23 19:29:38 +09:00 committed by Miguel Ojeda
parent b160dc46dd
commit b7ed2b6f4e
1 changed files with 1 additions and 1 deletions
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2
rust/kernel/alloc/layout.rs
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@ -45,7 +45,7 @@ pub const fn empty() -> Self {
/// When `len * size_of::<T>()` overflows or when `len * size_of::<T>() > isize::MAX`. /// When `len * size_of::<T>()` overflows or when `len * size_of::<T>() > isize::MAX`.
pub const fn new(len: usize) -> Result<Self, LayoutError> { pub const fn new(len: usize) -> Result<Self, LayoutError> {
match len.checked_mul(core::mem::size_of::<T>()) { match len.checked_mul(core::mem::size_of::<T>()) {
Some(len) if len <= ISIZE_MAX => { Some(size) if size <= ISIZE_MAX => {
// INVARIANT: We checked above that `len * size_of::<T>() <= isize::MAX`. // INVARIANT: We checked above that `len * size_of::<T>() <= isize::MAX`.
Ok(Self { Ok(Self {
len, len,