linux-kernel - Re: [PATCH] x86, cpuinfo x86_model

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Date:	Tue, 19 May 2015 21:22:06 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Igor Mammedov <imammedo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Prarit Bhargava <prarit@...hat.com>
Subject: Re: [PATCH] x86, cpuinfo x86_model_id whitespace cleanup

On Tue, May 19, 2015 at 11:44:41AM -0700, Andy Lutomirski wrote:
> On May 19, 2015 11:13 AM, "Borislav Petkov" <bp@...en8.de> wrote:
> >
> > On Tue, May 19, 2015 at 01:25:59PM -0400, Brian Gerst wrote:
> > > Using strlcpy in this manner could fail if it does larger than byte
> > > copies and they overlap.
> >
> > Why?
> >
> > AFAICT, strlcpy() calls memcpy() and memcpy should handle overlapping
> > buffers just fine.
> 
> Are you thinking of memmove?

I guess I'm trying to find out why don't we have a BIG FAT WARNING over
memcpy saying not to use it with overlapping buffers and larger than
byte sizes. Or maybe this is something everyone, except me, just knows
and that's a "Doh, Boris, of course!".

Btw, can we still avoid using the temporary buffer and use strncpy()
instead? AFAICT, that does byte copies, from looking at the asm.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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