linux-kernel - Re: [PATCH 05/18] iio: change strncpy+truncation to strlcpy

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Message-ID: <20180716114206.GA20555@nautica>
Date:   Mon, 16 Jul 2018 13:42:06 +0200
From:   Dominique Martinet <asmadeus@...ewreck.org>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/18] iio: change strncpy+truncation to strlcpy

Jonathan Cameron wrote on Sun, Jul 15, 2018:
> On Fri, 13 Jul 2018 03:25:34 +0200
> Dominique Martinet <asmadeus@...ewreck.org> wrote:
> > Generated by scripts/coccinelle/misc/strncpy_truncation.cocci
> > 
> > Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
> 
> Applied to the togreg branch of iio.git and pushed out as testing
> for the autobuilders to play with it.

Thanks!

I have been pointed out that strlcpy, unlike strncpy, will read past the
size given in the input string and thus is Bad™ if the input string is
not nul terminated.

After taking the time to check I believe this should not happen as the
original name seems to come from a dentry's d_name after proper
preparation (a buffer is allocated precisely for this purpose), but it
will not hurt to wait for that version.

The second reason I was waiting is that I intended to check for each
patch if it is safe to not pad the end of the string with zeroes (to
avoid e.g. information leaks) and that seems OK as well here after a
quick check but I wouldn't trust my own eyes this late so I'll let you
be judge of that if you feel like taking v1 anyway.

Otherwise, I'll recheck properly and submit a v2 with strscpy and a
better commit message after the coccinelle script is taken for inclusion
and doing a better check but this might take a while longer.

Thanks,
-- 
Dominique Martinet