Re: [RFC PATCH] xfs: fix FORTIFY_SOURCE complaints about log item memcpy

From: Kees Cook <keescook@chromium.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: h@magnolia, xfs <linux-xfs@vger.kernel.org>,
	Zorro Lang <zlang@redhat.com>,
	linux-hardening@vger.kernel.org
Subject: Re: [RFC PATCH] xfs: fix FORTIFY_SOURCE complaints about log item memcpy
Date: Tue, 25 Oct 2022 11:40:32 -0700	[thread overview]
Message-ID: <202210251139.3612057E@keescook> (raw)
In-Reply-To: <Y1cFxnea750izJd7@magnolia>

On Mon, Oct 24, 2022 at 02:38:14PM -0700, Darrick J. Wong wrote:
> <nod> I realized that these helpers introducing unsafe memcpy weren't
> needed.  Later on after chatting with dchinner a bit I came to the
> conclusion that we might as well convert most of the _copy_format
> functions to memcpy the structure head and flex array separately since
> that function is converting an ondisk log item into its in-memory
> representation, and some day we'll make those struct fields endian safe.
> They aren't now, and that's one of the (many) gaping holes that need
> fixing.

Ah, perfect! Yeah, this is one of the other standard solutions -- header
and flex array handled separately. I'm still working on APIs to handle
the common cases, though. XFS probably will want to keep it separate as
you've done.

> I sent my candidate fixes series to the list just now.

Thanks! I'll go check them out.

-- 
Kees Cook