netdev - Re: [PATCH net] tun: compare with 0 instead of total

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Message-ID: <1376597671.11676.149.camel@deadeye.wl.decadent.org.uk>
Date:	Thu, 15 Aug 2013 22:14:31 +0200
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	David Miller <davem@...emloft.net>
CC:	<wpan@...hat.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net] tun: compare with 0 instead of total_len

On Tue, 2013-08-13 at 19:29 -0700, David Miller wrote:
> From: Weiping Pan <wpan@...hat.com>
> Date: Tue, 13 Aug 2013 21:46:56 +0800
> 
> > Since we set "len = total_len" in the beginning of tun_get_user(),
> > so we should compare the new len with 0, instead of total_len,
> > or the if statement always returns false.
> > 
> > Signed-off-by: Weiping Pan <wpan@...hat.com>
> 
> Definitely looks correct to me, applied, thanks.

len is unsigned.  So while len > total_len is a poor way of checking for
underflow, len < 0 is much worse!

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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