From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:34245 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483AbcHRMpD (ORCPT ); Thu, 18 Aug 2016 08:45:03 -0400 Subject: Patch "mtd: nand: fix bug writing 1 byte less than page size" has been added to the 4.4-stable tree To: hector.palacios@digi.com, boris.brezillon@free-electrons.com, computersforpeace@gmail.com, gregkh@linuxfoundation.org Cc: , From: Date: Thu, 18 Aug 2016 14:44:36 +0200 Message-ID: <147152427613925@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled mtd: nand: fix bug writing 1 byte less than page size to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mtd-nand-fix-bug-writing-1-byte-less-than-page-size.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 144f4c98399e2c0ca60eb414c15a2c68125c18b8 Mon Sep 17 00:00:00 2001 From: Hector Palacios Date: Mon, 18 Jul 2016 10:39:18 +0200 Subject: mtd: nand: fix bug writing 1 byte less than page size From: Hector Palacios commit 144f4c98399e2c0ca60eb414c15a2c68125c18b8 upstream. nand_do_write_ops() determines if it is writing a partial page with the formula: part_pagewr = (column || writelen < (mtd->writesize - 1)) When 'writelen' is exactly 1 byte less than the NAND page size the formula equates to zero, so the code doesn't process it as a partial write, although it should. As a consequence the function remains in the while(1) loop with 'writelen' becoming 0xffffffff and iterating endlessly. The bug may not be easy to reproduce in Linux since user space tools usually force the padding or round-up the write size to a page-size multiple. This was discovered in U-Boot where the issue can be reproduced by writing any size that is 1 byte less than a page-size multiple. For example, on a NAND with 2K page (0x800): => nand erase.part => nand write $loadaddr 7ff [Editor's note: the bug was added in commit 29072b96078f, but moved around in commit 66507c7bc8895 ("mtd: nand: Add support to use nand_base poi databuf as bounce buffer")] Fixes: 29072b96078f ("[MTD] NAND: add subpage write support") Signed-off-by: Hector Palacios Acked-by: Boris Brezillon Signed-off-by: Brian Norris Signed-off-by: Greg Kroah-Hartman --- drivers/mtd/nand/nand_base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -2586,7 +2586,7 @@ static int nand_do_write_ops(struct mtd_ int cached = writelen > bytes && page != blockmask; uint8_t *wbuf = buf; int use_bufpoi; - int part_pagewr = (column || writelen < (mtd->writesize - 1)); + int part_pagewr = (column || writelen < mtd->writesize); if (part_pagewr) use_bufpoi = 1; Patches currently in stable-queue which might be from hector.palacios@digi.com are queue-4.4/mtd-nand-fix-bug-writing-1-byte-less-than-page-size.patch