In-Reply-To: <20050329142248.GA32455@nevyn.them.org>
References: <20050327205014.GD4285@stusta.de> <20050327232158.46146243.khali@linux-fr.org> <20050328222348.4c05e85c.akpm@osdl.org> <20050329142248.GA32455@nevyn.them.org>
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Cc: bunk@stusta.de, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, Jean Delvare <khali@linux-fr.org>
From: Kyle Moffett <mrmacman_g4@mac.com>
Subject: Re: Do not misuse Coverity please (Was: sound/oss/cs46xx.c: fix a check after use)
Date: Tue, 29 Mar 2005 17:37:19 -0500
To: Daniel Jacobowitz <dan@debian.org>
Sender: linux-kernel-owner@vger.kernel.org
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On Mar 29, 2005, at 09:22, Daniel Jacobowitz wrote:
> The thing GCC is most likely to do with this code is discard the NULL
> check entirely and leave only the oops; the "if (!card)" can not be
> reached without passing through "card->amplifier", and a pointer which
> is dereferenced can not be NULL in a valid program.

Not true!  It is perfectly legal on a large number of platforms to
explicitly mmap something at the address 0, at which point dereferencing
a null pointer is exactly like dereferencing any other pointer on the
heap.  Doing so is not recommended except in a few special cases for
emulators and such, but it works to some extent.

Cheers,
Kyle Moffett

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