linux-kernel - Re: [PATCH 4/4] UBI: replace MTD_UBI_BEB

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Date:	Mon, 20 Aug 2012 11:17:00 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Richard Genoud <richard.genoud@...il.com>
Cc:	Shmulik Ladkani <shmulik.ladkani@...il.com>,
	linux-mtd@...ts.infradead.org,
	David Woodhouse <dwmw2@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] UBI: replace MTD_UBI_BEB_LIMIT with user-space
 parameter

On Mon, 2012-08-20 at 08:55 +0200, Richard Genoud wrote:
> Hi Artem,
> 2012/8/19 Artem Bityutskiy <dedekind1@...il.com>:
> > Yeah, I wanted to make it 1..256 but forgot, will do now. 0..256 would
> > need some more work to avoid division by 0.
> Division by 0 is handled in the get_bad_peb_limit() function, I don't
> see another dangerous place.

        if (mult_frac(limit, 1024, max_beb_per1024) < device_pebs)

will divide by 0 if max_beb_per1024 is 0.

> (and if we want to be coherent with user-space, it should be 0..255,
> as the range is coded with an u8)

I think it should be uint16_t instead, because we are defining ABI here
and we should not assume no one will ever nee values higher than 255.

-- 
Best Regards,
Artem Bityutskiy

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