OneNAND: Do not allow oob write past end of page

From ba01b89188f21ca9a982e33452217e5c6874fd0b Mon Sep 17 00:00:00 2001

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Adrian Hunter
Sent: Friday, February 02, 2007 4:55 PM
To: [email protected]
Subject: [PATCH] [MTD] OneNAND: Do not allow oob write past end of page

Quoted 1 line

From ba01b89188f21ca9a982e33452217e5c6874fd0b Mon Sep 17

00:00:00 2001
From: Adrian Hunter <[email protected]>
Date: Thu, 1 Feb 2007 16:04:50 +0200
Subject: [MTD] OneNAND: Do not allow oob write past end of page

OneNAND can write oob to successive pages, but NAND does not do that. For compatibility, disallow OneNAND from writing past the end of the page.

Signed-off-by Adrian Hunter <[email protected]>

---
 drivers/mtd/onenand/onenand_base.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

drivers/mtd/onenand/onenand_base.c +1 -0

index 9ec28bb..b7da84a 100644
@@ -1191,6 +1191,13 @@ static int onenand_do_write_oob(struct m
 		return -EINVAL;
 	}
 
+	/* For compatibility with NAND: Do not allow write past 

end of page */

drivers/mtd/onenand/onenand_base.c +6 -1

+	if (column + len > oobsize) {
+		DEBUG(MTD_DEBUG_LEVEL0, "onenand_write_oob: "
+		      "Attempt to write past end of page\n");
+		return -EINVAL;
+	}
+
 	/* Do not allow reads past end of device */
 	if (unlikely(to >= mtd->size ||
 		     column + len > ((mtd->size >> this->page_shift) -
--

1.4.3

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Umm Why is it required in OneNAND? Even though OneNAND is based on NAND. We regard it as NOR

Quoted 2 lines · ext Kyungmin Park

Umm Why is it required in OneNAND? Even though OneNAND is based on NAND. We regard it as NOR

I am not sure what you mean. In onenand_base.c it has:

	mtd->type = MTD_NANDFLASH;

So mtd sees it as NAND.

I mean that in the view point of software OnenNAND is NAND, but the one of hardware it is NOR.
So we don't need to work it as NAND. I think we don't need to restrict the OneNAND

OneNAND stuff which we have now is _part of MTD_. MTD has its interface, its model of the device. As long as we are part of this infrastructure, we have to obey MTD's interface, rules and restrictions.

The whole idea of MTD is to make upper layers to access flashes in a uniform layer. MTD achieves this at certain extent. There are flaws, but anyway. So basically OneNAND implements more then NAND in this OOB handling stuff. And it is bad. It encourages other people to write OneNAND-only software, incompatible with NAND, which is totally unreasonable in this case.

BTW, after patch, we got dead code.
I downloaded oobtest again, re-run it and see that it trigger exception code in onenand_do_write_oob
But it don't touch following codes whether include your patch or not.

        /* Do not allow write past end of device */
        if (unlikely(to >= mtd->size ||
            column + len > ((mtd->size >> this->page_shift) -
                                (to >> this->page_shift)) * oobsize)) {
                DEBUG(MTD_DEBUG_LEVEL0, "onenand_write_oob: Attempted to
write past end of device\n");
                return -EINVAL;
        }

Please check oobtest program.

Thank you,
Kyungmin Park

--

oobtest: Test 4 of 5
oobtest: erasing
oobtest: erased 0
oobtest: erased 128
oobtest: Attempting to start write past end of oob
oobtest: An error is expected...
oobtest: Error occurred as expected
oobtest: Attempting to start read past end of oob
oobtest: An error is expected...
oobtest: Error occurred as expected
oobtest: Attempting to write past end of device
oobtest: An error is expected...
-> onenand_write_oob: Attempt to write past end of page
oobtest: Error occurred as expected
oobtest: Attempting to read past end of device
oobtest: An error is expected...

oobtest: error: read past end of device
oobtest: Attempting to write past end of device
oobtest: An error is expected...
-> onenand_write_oob: Attempt to write past end of page
oobtest: Error occurred as expected
oobtest: Attempting to read past end of device
oobtest: An error is expected...
oobtest: error: read past end of device

Seems ok for me:

oobtest: Attempting to start write past end of oob
oobtest: An error is expected...
onenand_write_oob: Attempted to start write outside oob
oobtest: Error occurred as expected
oobtest: Attempting to start read past end of oob
oobtest: An error is expected...
onenand_read_oob: Attempted to start read outside oob
oobtest: Error occurred as expected
oobtest: Attempting to write past end of device
oobtest: An error is expected...
onenand_write_oob: Attempted to write past end of device
oobtest: Error occurred as expected
oobtest: Attempting to read past end of device
oobtest: An error is expected...
onenand_read_oob: Attempted to read beyond end of device
oobtest: Error occurred as expected
oobtest: Attempting to write past end of device
oobtest: An error is expected...
onenand_write_oob: Attempted to write past end of device
oobtest: Error occurred as expected
oobtest: Attempting to read past end of device
oobtest: An error is expected...
onenand_read_oob: Attempted to read beyond end of device
oobtest: Error occurred as expected