Received-SPF: pass (google.com: domain of linux-kernel+bounces-35533-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Tue, 23 Jan 2024 16:30:05 +0100
From: Christian Brauner <brauner@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org, Benjamin LaHaise <bcrl@kvack.org>, 
	Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>, linux-aio@kvack.org, 
	linux-fsdevel@vger.kernel.org, "Gustavo A. R. Silva" <gustavoars@kernel.org>, 
	Bill Wendling <morbo@google.com>, Justin Stitt <justinstitt@google.com>, 
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 37/82] aio: Refactor intentional wrap-around test
Message-ID: <20240123-zerzausen-ahnen-02455c8a91bc@brauner>
References: <20240122235208.work.748-kees@kernel.org>
 <20240123002814.1396804-37-keescook@chromium.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20240123002814.1396804-37-keescook@chromium.org>

On Mon, Jan 22, 2024 at 04:27:12PM -0800, Kees Cook wrote:
> In an effort to separate intentional arithmetic wrap-around from
> unexpected wrap-around, we need to refactor places that depend on this
> kind of math. One of the most common code patterns of this is:
> 
> 	VAR + value < VAR
> 
> Notably, this is considered "undefined behavior" for signed and pointer
> types, which the kernel works around by using the -fno-strict-overflow
> option in the build[1] (which used to just be -fwrapv). Regardless, we
> want to get the kernel source to the position where we can meaningfully
> instrument arithmetic wrap-around conditions and catch them when they
> are unexpected, regardless of whether they are signed[2], unsigned[3],
> or pointer[4] types.
> 
> Refactor open-coded wrap-around addition test to use add_would_overflow().
> This paves the way to enabling the wrap-around sanitizers in the future.
> 
> Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1]
> Link: https://github.com/KSPP/linux/issues/26 [2]
> Link: https://github.com/KSPP/linux/issues/27 [3]
> Link: https://github.com/KSPP/linux/issues/344 [4]
> Cc: Benjamin LaHaise <bcrl@kvack.org>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: linux-aio@kvack.org
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---

What's the plan?
Merge the generic infrastructure and we can pick the individual patches?