kernel-hardening - RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy

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Date: Thu, 25 Jul 2019 07:26:14 +0000
From: "Gote, Nitin R" <nitin.r.gote@...el.com>
To: Joe Perches <joe@...ches.com>, Kees Cook <keescook@...omium.org>
CC: "corbet@....net" <corbet@....net>, "akpm@...ux-foundation.org"
	<akpm@...ux-foundation.org>, "apw@...onical.com" <apw@...onical.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad
 over strcpy/strlcpy/strncpy


> -----Original Message-----
> From: Joe Perches [mailto:joe@...ches.com]
> Sent: Wednesday, July 24, 2019 11:59 PM
> To: Gote, Nitin R <nitin.r.gote@...el.com>; Kees Cook
> <keescook@...omium.org>
> Cc: corbet@....net; akpm@...ux-foundation.org; apw@...onical.com;
> linux-doc@...r.kernel.org; kernel-hardening@...ts.openwall.com
> Subject: Re: [PATCH v5] Documentation/checkpatch: Prefer
> strscpy/strscpy_pad over strcpy/strlcpy/strncpy
> 
> On Wed, 2019-07-24 at 18:17 +0000, Gote, Nitin R wrote:
> > Hi,
> 
> Hi again.
> 
> []
> > > > > > 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
> 
> Please remember there does not exist a single actual use of strscpy_pad in
> the kernel sources and no apparent real need for it.  I don't find one anyway.
>

Thanks for clarification. I will remove strscpy_pad() from patch. 

> > Could you please give your opinion on below comment.
> >
> > > But, if the destination buffer needs extra NUL-padding for remaining
> > > size of destination, then safe replacement is strscpy_pad().  Right?
> > > If yes, then what is your opinion on below change :
> > >
> > >         "strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated
> > > uses,
> > > strncpy() dst should be __nonstring",
> > >
> > If you agree on this, then I will include this change in next patch version.
> 
> Two things:
> 
> The kernel-doc documentation uses dest not dst.

Noted. I will correct this.

> I think stracpy should be preferred over strscpy.
> 

Agreed. 
I will use stracpy() instead of strscpy().

Thanks,
Nitin

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