linux-kernel - Re: [PATCH 1/1] mtd: nand: add check for out of page read

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Date:	Tue, 14 Dec 2010 17:26:49 +0200
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Jason Liu <r64343@...escale.com>
Cc:	David.Woodhouse@...el.com, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] mtd: nand: add check for out of page read

On Fri, 2010-11-19 at 16:40 +0800, Jason Liu wrote:
> When run mtd_oobtest case, there will be one error for step(4),
> which turned out it need add one check for out of page read in
> nand_do_read_oob just like mtd_do_write_oob did it already.
> This commit also fix one typo error for comments in mtd_do_write_oob
> 
> Signed-off-by: Jason Liu <r64343@...escale.com>

I cannot reproduce this with nandsim, can you?

I tried:

1. sudo modprobe nandsim
   sudo modprobe mtd_oobtest dev=0

2. sudo ./load_nandsim.sh 128 128 2048
   sudo modprobe mtd_oobtest dev=0

In both cases the test passes: "mtd_oobtest: finished with 0 errors"

And in 'nand_do_read_oob()' I see the following piece of code:

        /* Do not allow reads past end of device */
        if (unlikely(from >= mtd->size ||
                     ops->ooboffs + readlen > ((mtd->size >> chip->page_shift) -
                                        (from >> chip->page_shift)) * len)) {
                DEBUG(MTD_DEBUG_LEVEL0, "%s: Attempt read beyond end "
                                        "of device\n", __func__);
                return -EINVAL;
        }

which should handle the case AFAICS.

So, although I did think hard about this, it looks like there is no
problem. What is the kernel version you are looking at? I checked it
with my l2-mtd-2.6.git, which is the latest mtd-2.6.git plus a revert
commit of your patch:

http://git.infradead.org/users/dedekind/l2-mtd-2.6.git

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

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