linux-kernel - Re: [PATCH 32/38] fs/cachefiles: remove invalid checks

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Date:	Mon, 21 Sep 2015 14:48:46 +0100
From:	David Howells <dhowells@...hat.com>
To:	Andrzej Hajda <a.hajda@...sung.com>
Cc:	dhowells@...hat.com, linux-kernel@...r.kernel.org,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-cachefs@...hat.com
Subject: Re: [PATCH 32/38] fs/cachefiles: remove invalid checks

Andrzej Hajda <a.hajda@...sung.com> wrote:

> The problem has been detected using proposed semantic patch
> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].

This is a problem in your test.  There's no actual problem with the code.

> -	ASSERT(cache->fstop_percent >= 0 &&

This is fine.  The compiler should just ignore it.

> -	       cache->fstop_percent < cache->fcull_percent &&
> -	       cache->fcull_percent < cache->frun_percent &&
> -	       cache->frun_percent  < 100);
> +	ASSERT(cache->fstop_percent < cache->fcull_percent &&
> +	       cache->fcull_percent < cache->frun_percent);

You've lost the upper bound check.

> -	if (datalen < 0 || datalen > PAGE_SIZE - 1)
> -	if (fstop < 0 || fstop >= cache->fcull_percent)
> -	if (bstop < 0 || bstop >= cache->bcull_percent)

These are all fine.  The compiler should just ignore them.

David
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