linux-kernel - Re: [PATCH] binder: check offset alignment in binder_get

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Message-ID: <20240418102046.GA2329396@google.com>
Date: Thu, 18 Apr 2024 11:20:46 +0100
From: Lee Jones <lee@...nel.org>
To: Carlos Llamas <cmllamas@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Christian Brauner <brauner@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	linux-kernel@...r.kernel.org, kernel-team@...roid.com,
	Alice Ryhl <aliceryhl@...gle.com>, stable@...r.kernel.org,
	Todd Kjos <tkjos@...gle.com>
Subject: Re: [PATCH] binder: check offset alignment in binder_get_object()

On Sat, 30 Mar 2024, Carlos Llamas wrote:

> Commit 6d98eb95b450 ("binder: avoid potential data leakage when copying
> txn") introduced changes to how binder objects are copied. In doing so,
> it unintentionally removed an offset alignment check done through calls
> to binder_alloc_copy_from_buffer() -> check_buffer().
> 
> These calls were replaced in binder_get_object() with copy_from_user(),
> so now an explicit offset alignment check is needed here. This avoids
> later complications when unwinding the objects gets harder.
> 
> It is worth noting this check existed prior to commit 7a67a39320df
> ("binder: add function to copy binder object from buffer"), likely
> removed due to redundancy at the time.
> 
> Fixes: 6d98eb95b450 ("binder: avoid potential data leakage when copying txn")
> Cc: stable@...r.kernel.org
> Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
> ---
>  drivers/android/binder.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Thanks for chasing this one down Carlos.

Reviewed-by: Lee Jones <lee@...nel.org>

-- 
Lee Jones [李琼斯]