linux-kernel - Re: [PATCH 2/6] lib/string: Fix erroneous 'overflow' documentation

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Message-ID: <20190221051736.GD11758@eros.localdomain>
Date:   Thu, 21 Feb 2019 16:17:36 +1100
From:   "Tobin C. Harding" <me@...in.cc>
To:     Kees Cook <keescook@...omium.org>
Cc:     "Tobin C. Harding" <tobin@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] lib/string: Fix erroneous 'overflow' documentation

On Wed, Feb 20, 2019 at 04:02:37PM -0800, Kees Cook wrote:
> On Mon, Feb 18, 2019 at 3:24 PM Tobin C. Harding <tobin@...nel.org> wrote:
> >
> > Current documentation uses 'overflow' to describe a situation where less
> > data is written to a buffer than buffer size not more.  'overflow' is
> > the wrong word here - since we don't typically say 'underflow' change
> > the whole sentence.
> >
> > Fix erroneous 'overflow' documentation for under filled buffer.
> >
> > Signed-off-by: Tobin C. Harding <tobin@...nel.org>
> > ---
> >  lib/string.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/string.c b/lib/string.c
> > index 38e4ca08e757..7f1d72db53c5 100644
> > --- a/lib/string.c
> > +++ b/lib/string.c
> > @@ -173,8 +173,8 @@ EXPORT_SYMBOL(strlcpy);
> >   *
> >   * Preferred to strncpy() since it always returns a valid string, and
> >   * doesn't unnecessarily force the tail of the destination buffer to be
> > - * zeroed.  If the zeroing is desired, it's likely cleaner to use strscpy()
> > - * with an overflow test, then just memset() the tail of the dest buffer.
> > + * zeroed.  If the zeroing is desired, it's likely cleaner to use strscpy(),
> > + * check the return size, then just memset() the tail of the dest buffer.
> >   */
> 
> I'd just fold this patch into the strscpy_zeroed() patch. No need for
> a kind of "no op" change here when we'll just change it again with a
> better advice ("use strscpy_zeroed()!")

Got it.

thanks,
Tobin.