linux-kernel - Re: [PATCH v1 2/9] pktcdvd: replace sscanf() by kstrtoul()

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Message-ID: <Y8p/Zh22evztnaEj@smile.fi.intel.com>
Date:   Fri, 20 Jan 2023 13:47:50 +0200
From:   'Andy Shevchenko' <andriy.shevchenko@...ux.intel.com>
To:     David Laight <David.Laight@...lab.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/9] pktcdvd: replace sscanf() by kstrtoul()

On Thu, Jan 19, 2023 at 10:40:12PM +0000, David Laight wrote:
> From: Andy Shevchenko
> > Sent: 19 January 2023 22:08

...

> > +	ret = kstrtoint(buf, 10, &val);
> > +	if (ret)
> > +		return ret;

> These don't look directly equivalent.
> The sscanf() version silently ignores trailing characters.
> I think kstrtoint() will generate an error.

Yes, kstrtoint() is stricter than sscanf(), but I believe
that user space not so abusive. We may always return to
sscanf(), which I don't think would be good idea rather
than fixing the user space. But let's see...

> Have you actually checked that the caller allows for
> an error return.

_s_size_t somehow hints us about :-)

-- 
With Best Regards,
Andy Shevchenko