netdev - Re: [Patch net v2] net: check dev->addr_len for dev_set_mac

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Message-Id: <20170729.112552.37407845739598905.davem@davemloft.net>
Date:   Sat, 29 Jul 2017 11:25:52 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     xiyou.wangcong@...il.com
Cc:     netdev@...r.kernel.org, andreyknvl@...gle.com, jiri@...nulli.us
Subject: Re: [Patch net v2] net: check dev->addr_len for
 dev_set_mac_address()

From: Cong Wang <xiyou.wangcong@...il.com>
Date: Wed, 26 Jul 2017 15:22:06 -0700

> Historically, dev_ifsioc() uses struct sockaddr as mac
> address definition, this is why dev_set_mac_address()
> accepts a struct sockaddr pointer as input but now we
> have various types of mac addresse whose lengths
> are up to MAX_ADDR_LEN, longer than struct sockaddr,
> and saved in dev->addr_len.
> 
> It is too late to fix dev_ifsioc() due to API
> compatibility, so just reject those larger than
> sizeof(struct sockaddr), otherwise we would read
> and use some random bytes from kernel stack.
> 
> Fortunately, only a few IPv6 tunnel devices have addr_len
> larger than sizeof(struct sockaddr) and they don't support
> ndo_set_mac_addr(). But with team driver, in lb mode, they
> can still be enslaved to a team master and make its mac addr
> length as the same.
> 
> Cc: Jiri Pirko <jiri@...nulli.us>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

Applied.