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

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Date:	Thu, 28 Apr 2016 17:47:31 +0100
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Kees Cook <keescook@...omium.org>
Cc:	Ingo Molnar <mingo@...nel.org>, Yinghai Lu <yinghai@...nel.org>,
	Baoquan He <bhe@...hat.com>, Borislav Petkov <bp@...e.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	"H.J. Lu" <hjl.tools@...il.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Andy Lutomirski <luto@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/boot: Rename overlapping memcpy() to memmove()

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