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From: Kevin Dawson <kevind@esi.com.au>
To: wharms@bfs.de
Cc: linux-hams@vger.kernel.org, netdev <netdev@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] ax25: unsigned cannot be less than 0 in ax25_ctl_ioctl()
Date: Wed, 14 Oct 2009 08:50:15 +1100	[thread overview]
Message-ID: <4AD4F617.4090300@cerebellum.kd> (raw)
In-Reply-To: <4AD44CF6.1070801@bfs.de>

walter harms wrote:
> 
> Kevin Dawson schrieb:
>> 
>>     if (ax25_ctl.arg > ULONG_MAX / HZ && ...
> 
> i like this because it prevents a wrap around for stupid ax25_ctl.arg values but will not help when
> ax25_ctl.arg * HZ is used later. NTL i think HZ does not need to be constant these days but i am not an
> expert on that area.

I don't have a kernel source tree at the moment, so I haven't seen where 
it's used, but the same size-limiting principle using divisions would 
apply whether you have constants, variables or function calls.

If ax25_ctl.arg * HZ is used later, one should arrange that the thread 
won't get that far if it has already been deemed an excessive value.

Kevin

  reply	other threads:[~2009-10-13 21:50 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-10 21:22 [PATCH] ax25: unsigned cannot be less than 0 in ax25_ctl_ioctl() Roel Kluin
2009-10-12 15:37 ` walter harms
2009-10-12 19:02   ` Roel Kluin
2009-10-12 21:58     ` Kevin Dawson
2009-10-13  9:48       ` walter harms
2009-10-13 21:50         ` Kevin Dawson [this message]
2009-10-14 15:26       ` Roel Kluin
2009-10-30  6:06         ` David Miller

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