linux-kernel - Re: [PATCH v2 2/2] mtd: spinand: micron: fixing the offset for OOB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230822153556.630e65b9@xps-13>
Date:   Tue, 22 Aug 2023 15:35:56 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Martin Kurbanov <mmkurbanov@...rdevices.ru>
Cc:     Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-kernel@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
        <kernel@...rdevices.ru>
Subject: Re: [PATCH v2 2/2] mtd: spinand: micron: fixing the offset for OOB

Hi Martin,

mmkurbanov@...rdevices.ru wrote on Tue, 22 Aug 2023 15:25:34 +0300:

> The first 4 bytes are reserved for bad block data.

Are you sure about that? I've never seen 4-bytes BBM.

> Signed-off-by: Martin Kurbanov <mmkurbanov@...rdevices.ru>
> ---
>  drivers/mtd/nand/spi/micron.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/spi/micron.c b/drivers/mtd/nand/spi/micron.c
> index 12601bc4227a..64b41c7c9cce 100644
> --- a/drivers/mtd/nand/spi/micron.c
> +++ b/drivers/mtd/nand/spi/micron.c
> @@ -57,6 +57,20 @@ static SPINAND_OP_VARIANTS(x1_write_cache_variants,
>  static SPINAND_OP_VARIANTS(x1_update_cache_variants,
>  			   SPINAND_PROG_LOAD(false, 0, NULL, 0));
>  
> +/*
> + * OOB spare area map (128 and 256 bytes)
> + *
> + *           +-----+-----------------+-------------------+---------------------+
> + *           | BBM |     Non ECC     |   ECC protected   |      ECC Area       |
> + *           |     | protected Area  |       Area        |                     |
> + * ----------+-----+-----------------+-------------------+---------------------+
> + *  oobsize  | 0:3 | 4:31 (28 bytes) | 32:63 (32 bytes)  | 64:127 (64 bytes)   |
> + * 128 bytes |     |                 |                   |                     |
> + * ----------+-----+-----------------+-------------------+---------------------+
> + *  oobsize  | 0:3 | 4:63 (60 bytes) | 64:127 (64 bytes) | 127:255 (128 bytes) |
> + * 256 bytes |     |                 |                   |                     |
> + * ----------+-----+-----------------+-------------------+---------------------+
> + */
>  static int micron_8_ooblayout_ecc(struct mtd_info *mtd, int section,
>  				  struct mtd_oob_region *region)
>  {
> @@ -75,9 +89,9 @@ static int micron_8_ooblayout_free(struct mtd_info *mtd, int section,
>  	if (section)
>  		return -ERANGE;
>  
> -	/* Reserve 2 bytes for the BBM. */
> -	region->offset = 2;
> -	region->length = (mtd->oobsize / 2) - 2;
> +	/* Reserve 4 bytes for the BBM. */
> +	region->offset = 4;
> +	region->length = (mtd->oobsize / 2) - 4;
>  
>  	return 0;
>  }


Thanks,
Miquèl