Re: [PATCH v2] x86/boot: Rename overlapping memcpy() to memmove()

From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>, Yinghai Lu <yinghai@kernel.org>,
	Baoquan He <bhe@redhat.com>, Borislav Petkov <bp@suse.de>,
	Ingo Molnar <mingo@redhat.com>, "x86@kernel.org" <x86@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	"H.J. Lu" <hjl.tools@gmail.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Andy Lutomirski <luto@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] x86/boot: Rename overlapping memcpy() to memmove()
Date: Thu, 28 Apr 2016 17:47:31 +0100	[thread overview]
Message-ID: <20160428174731.042b7394@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <CAGXu5jJLEi2pkdMg6xfQiu-SHJuUaftTC+vShm5+ZyqV7GQZgw@mail.gmail.com>

O> For example, this is what I've got currently:
> 
> /* Detect and warn about potential overlaps. */
> void *memcpy(void *dest, const void *src, size_t n)
> {
>         if (dest > src && dest - src < n)
>                 warn("Potentially unsafe overlapping memcpy detected!");
>         return __memcpy(dest, src, n);
> }
> 
> Does that seem okay? If so, I'll send the patch...

Probably useful for debug, but instead of relying on __memcpy
happening to handle overlaps - which isn't portable you could instead
debug all platforms by doing

	if (...) {
		warn(...)
		memmove()
	} else
		__memcpy


Alan