Messages in this thread | | | Date | Thu, 15 Sep 2016 18:06:05 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH BUGFIX] mtd: nand: mxc: fix obiwan error in mxc_nand_v[12]_ooblayout_free() functions |
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Hi Lothar,
On Fri, 9 Sep 2016 16:44:11 +0200 Lothar Waßmann <LW@KARO-electronics.de> 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 <LW@KARO-electronics.de> > --- > 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) {
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