netdev - Re: [PATCH] net: rtnl: avoid uninitialized data in IFLA_VF_VLAN

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Message-ID: <CAJ3xEMih26x2BFgokoapX6_gXSAh+wwRNS1i-vjsBifthiM20A@mail.gmail.com>
Date:   Fri, 30 Sep 2016 23:12:40 +0300
From:   Or Gerlitz <gerlitz.or@...il.com>
To:     Arnd Bergmann <arnd@...db.de>, Moshe Shemesh <moshe@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Brenden Blanco <bblanco@...mgrid.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Nogah Frankel <nogahf@...lanox.com>,
        Linux Netdev List <netdev@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: rtnl: avoid uninitialized data in IFLA_VF_VLAN_LIST handling

On Fri, Sep 30, 2016 at 7:13 PM, Arnd Bergmann <arnd@...db.de> wrote:
> With the newly added support for IFLA_VF_VLAN_LIST netlink messages,
> we get a warning about potential uninitialized variable use in
> the parsing of the user input when enabling the -Wmaybe-uninitialized
> warning:
>
> net/core/rtnetlink.c: In function 'do_setvfinfo':
> net/core/rtnetlink.c:1756:9: error: 'ivvl$' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> I have not been able to prove whether it is possible to arrive in
> this code with an empty IFLA_VF_VLAN_LIST block, but if we do,
> then ndo_set_vf_vlan gets called with uninitialized arguments.
>
> This adds an explicit check for an empty list, making it obvious
> to the reader and the compiler that this cannot happen.
>
> Fixes: 79aab093a0b5 ("net: Update API for VF vlan protocol 802.1ad support")
Added the authors of the above patch

> Signed-off-by: Arnd Bergmann <arnd@...db.de>