linux-kernel - Re: [PATCH] core: dev: don't call BUG() on bad input

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Message-ID: <20110214122313.GA10062@albatros>
Date:	Mon, 14 Feb 2011 15:23:13 +0300
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Nicolas de Pesloüan 
	<nicolas.2p.debian@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Tom Herbert <therbert@...gle.com>,
	Changli Gao <xiaosuo@...il.com>,
	Jesse Gross <jesse@...ira.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] core: dev: don't call BUG() on bad input

Hi Nicolas,

On Mon, Feb 14, 2011 at 13:16 +0100, Nicolas de Pesloüan wrote:
> >-	BUG_ON(strlen(name)>= sizeof(dev->name));
> >+	if (strnlen(name, sizeof(dev->name))>= sizeof(dev->name)) {

Ehh...  Space after ")" is needed :)

> "size_t strnlen(const char *s, size_t maxlen) : The strnlen()
> function returns strlen(s), if that is less than maxlen, or maxlen
> if there is no '\0' character among the first maxlen characters
> pointed to by s."
> 
> How can strnlen(name, sizeof(dev->name)) be greater than sizeof(dev->name)?
> 
> Shouldn't it be "if (strnlen(name, sizeof(dev->name)) == sizeof(dev->name))" instead?

Not a big deal, but MO it's better to guard from everything that
is not a good input by negating the check.  strnlen() < sizeof() is OK,
strnlen() >= sizeof() is bad.  Is "==" more preferable for net/ coding style?


-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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