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From:   Boqun Feng <boqun.feng@gmail.com>
To:     rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
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Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
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        Kees Cook <keescook@chromium.org>, stable@vger.kernel.org
Subject: [PATCH 2/3] rust: allocator: Use krealloc_aligned() in KernelAllocator::alloc
Date:   Sat, 29 Jul 2023 18:29:03 -0700
Message-ID: <20230730012905.643822-3-boqun.feng@gmail.com>
In-Reply-To: <20230730012905.643822-1-boqun.feng@gmail.com>
References: <20230730012905.643822-1-boqun.feng@gmail.com>
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This fixes the potential issue that when KernelAllocator is used, the
allocation may be mis-aligned due to SLAB's alignment guarantee.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 rust/kernel/allocator.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index fae11d1fdba7..1aec688cf0e0 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/allocator.rs
@@ -41,9 +41,9 @@ unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gf
 
 unsafe impl GlobalAlloc for KernelAllocator {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        // `krealloc()` is used instead of `kmalloc()` because the latter is
-        // an inline function and cannot be bound to as a result.
-        unsafe { bindings::krealloc(ptr::null(), layout.size(), bindings::GFP_KERNEL) as *mut u8 }
+        // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
+        // requirement.
+        unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
-- 
2.41.0