From: Asahi Lina <lina@asahilina.net>
Date: Fri, 7 Mar 2025 22:50:07 +0000 (+0100)
Subject: rust: alloc: Fix `ArrayLayout` allocations
X-Git-Tag: v6.12.19~200
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84fc3616b206eeba1b9de84cbaa6b6cf06bad62d;p=thirdparty%2Fkernel%2Fstable.git

rust: alloc: Fix `ArrayLayout` allocations

commit b7ed2b6f4e8d7f64649795e76ee9db67300de8eb upstream.

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: 9e7bbfa18276 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/rust/kernel/alloc/layout.rs b/rust/kernel/alloc/layout.rs
index 7e0c2f46157b7..4b3cd7fdc816c 100644
--- a/rust/kernel/alloc/layout.rs
+++ b/rust/kernel/alloc/layout.rs
@@ -45,7 +45,7 @@ impl<T> ArrayLayout<T> {
     /// When `len * size_of::<T>()` overflows or when `len * size_of::<T>() > isize::MAX`.
     pub const fn new(len: usize) -> Result<Self, LayoutError> {
         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`.
                 Ok(Self {
                     len,