linux-kernel - Re: [PATCH 06/10] parse

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Date:	Mon, 04 May 2015 16:33:12 +0200
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/10] parse_integer: convert mm/

On Sat, May 02 2015, Alexey Dobriyan <adobriyan@...il.com> wrote:

> Convert mm/ directory away from deprecated simple_strto*() interface.
>
> One thing to note about parse_integer() and seemingly useless casts --
> range of accepted values depends on result type.
>
> 	int val;
> 	parse_integer(s, 0, &val);
>
> will accept negative integers, while
>
> 	int val;
> 	parse_integer(s, 0, (unsigned int *)&val);
>
> will accept only 0 and positive integers.

... and then silently write a negative value to val if the parsed
integer happens to be larger than INT_MAX.

Again, I think passing cast expressions to parse_integer should be
verboten.

In these particular cases:

* memtest_pattern should just be unsigned int - it's only ever used as
  such anyway, and it represents a count.

* hashdist should be a boolean, but even in its current form, there's no
  reason to not just use parse_integer as-is. If people like to set it
  by passing -42 just let them.

Rasmus
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