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From: daw@cs.berkeley.edu (David Wagner)
To: linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] mm: Remove ZERO_SIZE_PTR.
Date: Fri, 26 Feb 2010 18:23:06 +0000 (UTC)	[thread overview]
Message-ID: <hm93ia$15p$1@taverner.cs.berkeley.edu> (raw)
In-Reply-To: 201002260838.o1Q8cfr2068194@www262.sakura.ne.jp

Tetsuo Handa  wrote:
>This patch simplifies error checks of both callers/callees from
>
>	((unsigned long)(x) <= (unsigned long) 16)
>
>to
>
>	!(x)

I don't follow.  If you want to avoid integer overflow, the caller
of kmalloc() must check to make sure that the arithmetic operations
it performs do not overflow.  That's true whether or not your patch
is accepted.  An integer overflow in an arithmetic operation can yield
a non-zero value, so checking "!(x)" does not guarantee that there was
no integer overflow involved in the computation of x.

  parent reply	other threads:[~2010-02-26 18:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-26  6:35 [RFC][PATCH] mm: Remove ZERO_SIZE_PTR Tetsuo Handa
2010-02-26  6:59 ` KOSAKI Motohiro
2010-02-26  8:38   ` Tetsuo Handa
2010-02-26  8:44     ` KOSAKI Motohiro
2010-02-26 18:23     ` David Wagner [this message]
2010-02-26  7:26 ` David Wagner
2010-02-26 16:39 ` Christoph Lameter
2010-02-27  0:59   ` Tetsuo Handa
2010-03-03 21:54     ` Pavel Machek

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