From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754275AbcIOQG0 convert rfc822-to-8bit (ORCPT ); Thu, 15 Sep 2016 12:06:26 -0400 Received: from down.free-electrons.com ([37.187.137.238]:45636 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751979AbcIOQGS (ORCPT ); Thu, 15 Sep 2016 12:06:18 -0400 Date: Thu, 15 Sep 2016 18:06:05 +0200 From: Boris Brezillon To: Lothar =?UTF-8?B?V2HDn21hbm4=?= Cc: linux-arm-kernel@lists.infradead.org, Richard Weinberger , David Woodhouse , Brian Norris , linux-mtd@lists.infradead.org (open list:NAND FLASH SUBSYSTEM), linux-kernel@vger.kernel.org (open list) Subject: Re: [PATCH BUGFIX] mtd: nand: mxc: fix obiwan error in mxc_nand_v[12]_ooblayout_free() functions Message-ID: <20160915180605.4aed48d3@bbrezillon> In-Reply-To: <1473432251-24728-1-git-send-email-LW@KARO-electronics.de> References: <1473432251-24728-1-git-send-email-LW@KARO-electronics.de> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lothar, On Fri, 9 Sep 2016 16:44:11 +0200 Lothar Waßmann wrote: > commit a894cf6c5a82 ("mtd: nand: mxc: switch to mtd_ooblayout_ops") > introduced a regression accessing the OOB area from the mxc_nand > driver due to an Obiwan error in the mxc_nand_v[12]_ooblayout_free() > functions. They report a bogus oobregion { 64, 7 } which leads to > errors accessing bogus data when reading the oob area. > > Prior to the commit the mtd-oobtest module could be run without any > errors. With the offending commit, this test fails with results like: > |Running mtd-oobtest > | > |================================================= > |mtd_oobtest: MTD device: 5 > |mtd_oobtest: MTD device size 524288, eraseblock size 131072, page size 2048, count of eraseblocks 4, pages per eraseblock 64, OOB size 64 > |mtd_test: scanning for bad eraseblocks > |mtd_test: scanned 4 eraseblocks, 0 are bad > |mtd_oobtest: test 1 of 5 > |mtd_oobtest: writing OOBs of whole device > |mtd_oobtest: written up to eraseblock 0 > |mtd_oobtest: written 4 eraseblocks > |mtd_oobtest: verifying all eraseblocks > |mtd_oobtest: error @addr[0x0:0x19] 0x9a -> 0x78 diff 0xe2 > |mtd_oobtest: error @addr[0x0:0x1a] 0xcc -> 0x0 diff 0xcc > |mtd_oobtest: error @addr[0x0:0x1b] 0xe0 -> 0x85 diff 0x65 > |mtd_oobtest: error @addr[0x0:0x1c] 0x60 -> 0x62 diff 0x2 > |mtd_oobtest: error @addr[0x0:0x1d] 0x69 -> 0x45 diff 0x2c > |mtd_oobtest: error @addr[0x0:0x1e] 0xcd -> 0xa0 diff 0x6d > |mtd_oobtest: error @addr[0x0:0x1f] 0xf2 -> 0x60 diff 0x92 > |mtd_oobtest: error: verify failed at 0x0 > [...] > > Signed-off-by: Lothar Waßmann > --- > drivers/mtd/nand/mxc_nand.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c > index 5173fad..fdee907 100644 > --- a/drivers/mtd/nand/mxc_nand.c > +++ b/drivers/mtd/nand/mxc_nand.c > @@ -893,7 +893,7 @@ static int mxc_v1_ooblayout_free(struct mtd_info *mtd, int section, > { > struct nand_chip *nand_chip = mtd_to_nand(mtd); > > - if (section > nand_chip->ecc.steps) > + if (section >= nand_chip->ecc.steps) > return -ERANGE; Hm, looking at the commit you're pointing to, it seems that this test is correct (we have X + 1 free sections, where X is the number of ECC steps). > > if (!section) { > @@ -943,7 +943,7 @@ static int mxc_v2_ooblayout_free(struct mtd_info *mtd, int section, > struct nand_chip *nand_chip = mtd_to_nand(mtd); > int stepsize = nand_chip->ecc.bytes == 9 ? 16 : 26; > > - if (section > nand_chip->ecc.steps) > + if (section >= nand_chip->ecc.steps) > return -ERANGE; Yep, this one is a real bug. > > if (!section) {