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

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Message-Id: <20161003.013225.2126712838089878159.davem@davemloft.net>
Date:   Mon, 03 Oct 2016 01:32:25 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     arnd@...db.de
Cc:     roopa@...ulusnetworks.com, nicolas.dichtel@...nd.com,
        nikolay@...ulusnetworks.com, jiri@...lanox.com,
        edumazet@...gle.com, bblanco@...mgrid.com,
        hannes@...essinduktion.org, nogahf@...lanox.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: rtnl: avoid uninitialized data in
 IFLA_VF_VLAN_LIST handling

From: Arnd Bergmann <arnd@...db.de>
Date: Fri, 30 Sep 2016 18:13:49 +0200

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

Applied, thanks.