netdev - RE: [PATCH net-next] net: ndisc.c: reduce size of __ndisc_fill_addr

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Date:   Wed, 31 May 2017 00:06:32 +0000
From:   YUAN Linyu <Linyu.Yuan@...atel-sbell.com.cn>
To:     Joe Perches <joe@...ches.com>, David Miller <davem@...emloft.net>,
        "cugyly@....com" <cugyly@....com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "dsahern@...il.com" <dsahern@...il.com>
Subject: RE: [PATCH net-next] net: ndisc.c: reduce size of
 __ndisc_fill_addr_option()

Hi joe,

> -----Original Message-----
> From: netdev-owner@...r.kernel.org [mailto:netdev-owner@...r.kernel.org]
> On Behalf Of Joe Perches
> Sent: Tuesday, May 30, 2017 11:41 AM
> To: David Miller; cugyly@....com
> Cc: netdev@...r.kernel.org; dsahern@...il.com; YUAN Linyu
> Subject: Re: [PATCH net-next] net: ndisc.c: reduce size of
> __ndisc_fill_addr_option()
> 
> On Mon, 2017-05-29 at 23:30 -0400, David Miller wrote:
> > From: yuan linyu <cugyly@....com>
> > Date: Sat, 27 May 2017 06:00:52 +0800
> >
> > > From: yuan linyu <Linyu.Yuan@...atel-sbell.com.cn>
> > >
> > > Signed-off-by: yuan linyu <Linyu.Yuan@...atel-sbell.com.cn>
> >
> > Applied, thanks.
> 
> OK, but is it really safe though?
> 
> Could "space" (an int) ever be negative after
> subtracting "pad" and "data_len"?
It's safe, check
int space = __ndisc_opt_addr_space(data_len, pad);
space is maximum aligned value.
And I check current pad, the maximum value is 2.