From: "Jörn Engel" <joern@logfs.org>
To: Roel Kluin <12o3l@tiscali.nl>
Cc: linux-mtd@lists.infradead.org, dwmw2@infradead.org
Subject: Re: [MTD] potential division by 0 in cfi_build_cmd() and cfi_merge_status()?
Date: Tue, 15 Jan 2008 04:01:03 +0100 [thread overview]
Message-ID: <20080115030103.GA19407@lazybastard.org> (raw)
In-Reply-To: <478BFE1C.1090608@tiscali.nl>
On Tue, 15 January 2008 01:28:12 +0100, Roel Kluin wrote:
>
> Doing some grepping, I stumbled upon this possible error:
>
> in include/linux/mtd/cfi.h, lines 302 and 366, resp. functions
> cfi_build_cmd() and cfi_merge_status() there is a division by
> cfi_interleave(cfi):
>
> chip_mode = map_bankwidth(map) / cfi_interleave(cfi);
>
> This could be problematic when No CONFIG_MTD_CFI_Ix is selected:
> cfi_interleave will triggers BUG(), but when BUG is disabled, the
> function returns 0, causing a subsequent division by zero.
>
> When a CONFIG_MTD_CFI_Ix is selected, cfi_interleave(cfi) is either
> defined 1 or defined (cfi)->interleave.
>
> cfi is a struct cfi_private pointer, with interleave as an int.
>
> I am not sure whether interleave can ever be 0 in this division when
> CONFIG_MTD_CFI_Ix is set.
>
> shouldn't there be an error exit when cfi_interleave(cfi) evaluates
> to 0?
I don't think cfi_interleave(cfi) will ever be 0. But the functions
definitely look a bit large for inlines. Anyone having both cfi_probe
and jedec_probe will enjoy twice the kernel footprint from them.
Patches to move that code out-of-line are welcome.
Jörn
--
Fools ignore complexity. Pragmatists suffer it.
Some can avoid it. Geniuses remove it.
-- Perlis's Programming Proverb #58, SIGPLAN Notices, Sept. 1982
next prev parent reply other threads:[~2008-01-15 3:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-15 0:28 [MTD] potential division by 0 in cfi_build_cmd() and cfi_merge_status()? Roel Kluin
2008-01-15 3:01 ` Jörn Engel [this message]
2008-01-15 4:06 ` Nicolas Pitre
2008-01-15 4:10 ` Jörn Engel
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