Re: [PATCH v1] mtd: rawnand: meson: check buffer length

[Miquel Raynal]

Hi Arseniy,

AVKrasnov@xxxxxxxxxxxxxx wrote on Mon, 5 Jun 2023 22:10:46 +0300:

> Meson NAND controller has limited buffer length, so check it before
> command execution to avoid length trim. Also check MTD write size on
> chip attach.

Almost there :)

> 
> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> ---
>  drivers/mtd/nand/raw/meson_nand.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index 074e14225c06..bfb5363cac23 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -108,6 +108,8 @@
>  
>  #define PER_INFO_BYTE		8
>  
> +#define NFC_CMD_RAW_LEN	GENMASK(13, 0)
> +
>  struct meson_nfc_nand_chip {
>  	struct list_head node;
>  	struct nand_chip nand;
> @@ -280,7 +282,7 @@ static void meson_nfc_cmd_access(struct nand_chip *nand, int raw, bool dir,
>  
>  	if (raw) {
>  		len = mtd->writesize + mtd->oobsize;
> -		cmd = (len & GENMASK(13, 0)) | scrambler | DMA_DIR(dir);
> +		cmd = len | scrambler | DMA_DIR(dir);
>  		writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  		return;
>  	}
> @@ -544,7 +546,7 @@ static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, int len)
>  	if (ret)
>  		goto out;
>  
> -	cmd = NFC_CMD_N2M | (len & GENMASK(13, 0));
> +	cmd = NFC_CMD_N2M | len;
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  
>  	meson_nfc_drain_cmd(nfc);
> @@ -568,7 +570,7 @@ static int meson_nfc_write_buf(struct nand_chip *nand, u8 *buf, int len)
>  	if (ret)
>  		return ret;
>  
> -	cmd = NFC_CMD_M2N | (len & GENMASK(13, 0));
> +	cmd = NFC_CMD_M2N | len;
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  
>  	meson_nfc_drain_cmd(nfc);
> @@ -936,6 +938,9 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
>  			break;
>  
>  		case NAND_OP_DATA_IN_INSTR:
> +			if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
> +				return -EINVAL;

You need to refuse the operation earlier. That's what the check_op
boolean is about. Maybe you can take inspiration from anfc_check_op()
in the arasan controller.

> +
>  			buf = meson_nand_op_get_dma_safe_input_buf(instr);
>  			if (!buf)
>  				return -ENOMEM;
> @@ -944,6 +949,9 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
>  			break;
>  
>  		case NAND_OP_DATA_OUT_INSTR:
> +			if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
> +				return -EINVAL;

Same.

> +
>  			buf = meson_nand_op_get_dma_safe_output_buf(instr);
>  			if (!buf)
>  				return -ENOMEM;
> @@ -1181,6 +1189,7 @@ static int meson_nand_attach_chip(struct nand_chip *nand)
>  	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>  	struct mtd_info *mtd = nand_to_mtd(nand);
>  	int nsectors = mtd->writesize / 1024;
> +	int raw_writesize;
>  	int ret;
>  
>  	if (!mtd->name) {
> @@ -1192,6 +1201,13 @@ static int meson_nand_attach_chip(struct nand_chip *nand)
>  			return -ENOMEM;
>  	}
>  
> +	raw_writesize = mtd->writesize + mtd->oobsize;
> +	if (raw_writesize > NFC_CMD_RAW_LEN) {
> +		dev_err(nfc->dev, "too big write size in raw mode: %d > %ld\n",
> +			raw_writesize, NFC_CMD_RAW_LEN);
> +		return -EINVAL;
> +	}
> +
>  	if (nand->bbt_options & NAND_BBT_USE_FLASH)
>  		nand->bbt_options |= NAND_BBT_NO_OOB;
>  


Thanks,
Miquèl