netdev - Re: [PATCH v4 4/9] em28xx: fix em28xx_dvb

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Date:   Mon, 25 Sep 2017 23:32:08 -0700
From:   Arnd Bergmann <arnd@...db.de>
To:     David Laight <David.Laight@...lab.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Arend van Spriel <arend.vanspriel@...adcom.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <mmarek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "brcm80211-dev-list.pdl@...adcom.com" 
        <brcm80211-dev-list.pdl@...adcom.com>,
        "brcm80211-dev-list@...ress.com" <brcm80211-dev-list@...ress.com>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>,
        "linux-kbuild@...r.kernel.org" <linux-kbuild@...r.kernel.org>,
        Jakub Jelinek <jakub@....gnu.org>,
        Martin Liška <marxin@....gnu.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v4 4/9] em28xx: fix em28xx_dvb_init for KASAN

On Mon, Sep 25, 2017 at 7:41 AM, David Laight <David.Laight@...lab.com> wrote:
> From: Arnd Bergmann
>> Sent: 22 September 2017 22:29
> ...
>> It seems that this is triggered in part by using strlcpy(), which the
>> compiler doesn't recognize as copying at most 'len' bytes, since strlcpy
>> is not part of the C standard.
>
> Neither is strncpy().
>
> It'll almost certainly be a marker in a header file somewhere,
> so it should be possibly to teach it about other functions.

I'm currently travelling and haven't investigated in detail, but from
taking a closer look here, I found that the hardened 'strlcpy()'
in include/linux/string.h triggers it. There is also a hardened
(much shorted) 'strncpy()' that doesn't trigger it in the same file,
and having only the extern declaration of strncpy also doesn't.

        Arnd