From: Carlos Llamas <cmllamas@google.com>
To: Alice Ryhl <aliceryhl@google.com>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jann Horn" <jannh@google.com>, "Miguel Ojeda" <ojeda@kernel.org>,
"Boqun Feng" <boqun@kernel.org>, "Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <lossin@kernel.org>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Trevor Gross" <tmgross@umich.edu>,
"Danilo Krummrich" <dakr@kernel.org>,
"Lorenzo Stoakes" <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
linux-mm@kvack.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] rust_binder: check ownership before using vma
Date: Mon, 2 Mar 2026 17:18:30 +0000 [thread overview]
Message-ID: <aaXGZlfAmk-DCuBW@google.com> (raw)
In-Reply-To: <20260218-binder-vma-check-v2-1-60f9d695a990@google.com>
On Wed, Feb 18, 2026 at 11:53:26AM +0000, Alice Ryhl wrote:
> When installing missing pages (or zapping them), Rust Binder will look
> up the vma in the mm by address, and then call vm_insert_page (or
> zap_page_range_single). However, if the vma is closed and replaced with
> a different vma at the same address, this can lead to Rust Binder
> installing pages into the wrong vma.
>
> By installing the page into a writable vma, it becomes possible to write
> to your own binder pages, which are normally read-only. Although you're
> not supposed to be able to write to those pages, the intent behind the
> design of Rust Binder is that even if you get that ability, it should not
> lead to anything bad. Unfortunately, due to another bug, that is not the
> case.
This all makes sense to me. What I'm missing though is why not reject
VM_WRITE mappings all together? Is there a downside or something that
prevents us from setting this check?
--
Carlos Llamas
next prev parent reply other threads:[~2026-03-02 17:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-18 11:53 [PATCH v2 0/2] Fix VMA confusion in Rust Binder Alice Ryhl
2026-02-18 11:53 ` [PATCH v2 1/2] rust_binder: check ownership before using vma Alice Ryhl
2026-02-18 13:47 ` Danilo Krummrich
2026-02-18 15:54 ` Liam R. Howlett
2026-02-18 16:39 ` Alice Ryhl
2026-03-02 17:18 ` Carlos Llamas [this message]
2026-03-02 17:28 ` Jann Horn
2026-03-02 18:36 ` Carlos Llamas
2026-02-18 11:53 ` [PATCH v2 2/2] rust_binder: avoid reading the written value in offsets array Alice Ryhl
2026-02-18 16:02 ` Liam R. Howlett
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