netdev - Re: [PATCH] division-by-zero in inet_csk_get

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Message-ID: <m3wstvjnso.fsf@bandura.englab.brq.redhat.com>
Date:	Wed, 10 Oct 2007 11:56:23 +0200
From:	Anton Arapov <aarapov@...hat.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, den@...nvz.org
Subject: Re: [PATCH] division-by-zero in inet_csk_get_port

David Miller <davem@...emloft.net> writes:
>> Ok, I've got it, so we have to do the same with the following:
>> quote from inet_hashtables.c and inet6_hashtables.c. I'll prepare the
>> patch.
>> 
>> And just a curious, does the /* Treat low > high as high == low */
>> idea will keep after the sysctl will be patched?
>
> I'm beginning to think that we should do the sysctl validation
> in this patch too, instead of duplicating this grotty check
> in all of these port selection functions.
  Yep, that's exactly I'm talking about. I'm sure that 
  [...] % (high - low) [...] erroneous from the begining, because
in such places we want to have 1 in denominator, for the cases when we
have only one port. Because 34000 34000 in sysctl's
ip_local_port_range means 1(one) port, not 0(zero).

  So it seems to me that we have to fix mentioned denominators in
kernel/net to have 1, that will be correct logically. And do the
MAX<MIN check in sysctl code.
  From this point of view, it's best idea to have two patches: one for
the kernel/net denominators and another one for the sysctl.c's
function dointvec_minmax(). Because they can live independently. And
the patch for the kernel/net will do the work at least because we
prevent kernel trap at all.
  
  Dave, am I right?
-- 
Anton Arapov, <aarapov@...hat.com>
Kernel Development, Red Hat
GPG Key ID: 0x6FA8C812

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