linux-kernel - Re: revert "fs/befs/linuxvfs.c: replace strncpy by strlcpy"

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Message-ID: <CAMuHMdVxzQzj=PA3=5Lmk=rTaRTdpYYauQfXeY1waFYnQ7CeWQ@mail.gmail.com>
Date:	Wed, 29 Apr 2015 10:24:37 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Fabian Frederick <fabf@...net.be>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Subject: Re: revert "fs/befs/linuxvfs.c: replace strncpy by strlcpy"

On Wed, Apr 29, 2015 at 2:35 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> strncpy() has another use, though, and it can't be replaced by strlcpy() -
> see the commits that had started this thread.  IMO they (and anything
> else of the same nature) really need to be reverted; using strlcpy() on
> something that isn't guaranteed to be NUL-terminated is a serious bug.

To be honest, I never considered the "source is not NUL-terminated" case.
Strings in C (if they are strings, and not "buffers"; with buffers you
should know how many bytes are valid anyway) are always terminated ;-)

The other case we sometimes do want strncpy() for is the "crazy "fill with
NUL" at the end" feature, to avoid leaking sensitive data. The alternative
is to clear the target first, or the remainder afterwards.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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