linux-kernel - Re: [PATCH v4 4/5] mtd: rawnand: meson: check buffer length

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Date:   Mon, 22 May 2023 17:43:42 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Arseniy Krasnov <AVKrasnov@...rdevices.ru>
Cc:     Liang Yang <liang.yang@...ogic.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Yixun Lan <yixun.lan@...ogic.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>, <oxffffaa@...il.com>,
        <kernel@...rdevices.ru>, <linux-mtd@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 4/5] mtd: rawnand: meson: check buffer length

Hi Arseniy,

AVKrasnov@...rdevices.ru wrote on Mon, 15 May 2023 12:44:38 +0300:

> This NAND controller has limited buffer length, so check it before
> command execution to avoid length trim. Also check MTD write size on
> chip attach.
> 
> Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
> ---
>  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 a31106c943d7..dc0d7160520b 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -111,6 +111,8 @@
>  #define NFC_USER_BYTES		2
>  #define NFC_OOB_PER_ECC(nand)	((nand)->ecc.bytes + NFC_USER_BYTES)
>  
> +#define NFC_CMD_RAW_LEN		GENMASK(13, 0)
> +
>  struct meson_nfc_nand_chip {
>  	struct list_head node;
>  	struct nand_chip nand;
> @@ -284,7 +286,7 @@ 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;
>  	}
> @@ -562,6 +564,9 @@ static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, int len)
>  	u32 cmd;
>  	u8 *info;
>  
> +	if (len > NFC_CMD_RAW_LEN)
> +		return -EINVAL;
> +
>  	info = kzalloc(PER_INFO_BYTE, GFP_KERNEL);
>  	if (!info)
>  		return -ENOMEM;
> @@ -571,7 +576,7 @@ 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);
> @@ -590,12 +595,15 @@ static int meson_nfc_write_buf(struct nand_chip *nand, u8 *buf, int len)
>  	int ret = 0;
>  	u32 cmd;
>  
> +	if (len > NFC_CMD_RAW_LEN)
> +		return -EINVAL;

I think this helper is related to exec_op, if yes, you should probably
ask an early check in the exec_op implementation (perhaps as part of a
dedicated helper).

Same above.

Otherwise looks good.

> +
>  	ret = meson_nfc_dma_buffer_setup(nand, buf, len, NULL,
>  					 0, DMA_TO_DEVICE);
>  	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);
> @@ -1328,6 +1336,7 @@ 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) {
> @@ -1339,6 +1348,13 @@ 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