RE: [PATCH v2] mmc: arm_pl180: Limit data transfer to U16_MAX

["Jaehoon Chung" <jh80.chung@samsung.com>]

Hi,

> -----Original Message-----
> From: cmax@mailbox.org <cmax@mailbox.org>
> Sent: Thursday, April 4, 2024 3:58 PM
> To: u-boot@lists.denx.de
> Cc: Maximilian Brune <maximilian.brune@9elements.com>; Peng Fan <peng.fan@nxp.com>; Jaehoon Chung
> <jh80.chung@samsung.com>
> Subject: [PATCH v2] mmc: arm_pl180: Limit data transfer to U16_MAX
> 
> From: Maximilian Brune <maximilian.brune@9elements.com>
> 
> Currently fetching files bigger that cause a data transfer greater than
> U16_MAX fails.
> 
> The reason is that the specification defines the datalength register
> as a 16 bit wide register, but in u-boot it is used as if it is an
> 32 bit register. Therefore values greater than U16_MAX cause an
> infinite loop inside u-boot. U-boot expects to get more data from
> interface/hardware then it will ever get and therefore inifintely waits
> for more data that will never come.
> 
> Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>

Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>

Best Regards,
Jaehoon Chung

> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Jaehoon Chung <jh80.chung@samsung.com>
> ---
>  drivers/mmc/arm_pl180_mmci.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/mmc/arm_pl180_mmci.c b/drivers/mmc/arm_pl180_mmci.c
> index 5cf5502ed5..cad73ea106 100644
> --- a/drivers/mmc/arm_pl180_mmci.c
> +++ b/drivers/mmc/arm_pl180_mmci.c
> @@ -231,6 +231,7 @@ static int do_data_transfer(struct mmc *dev,
>  	u32 blksz = 0;
>  	u32 data_ctrl = 0;
>  	u32 data_len = (u32) (data->blocks * data->blocksize);
> +	assert(data_len < U16_MAX); /* should be ensured by arm_pl180_get_b_max */
> 
>  	if (!host->version2) {
>  		blksz = (ffs(data->blocksize) - 1);
> @@ -358,6 +359,14 @@ static int  host_set_ios(struct mmc *dev)
>  	return 0;
>  }
> 
> +static int arm_pl180_get_b_max(struct udevice *dev, void *dst, lbaint_t blkcnt)
> +{
> +	struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
> +	struct mmc *mmc = upriv->mmc;
> +
> +	return U16_MAX / mmc->read_bl_len;
> +}
> +
>  #ifndef CONFIG_DM_MMC
>  /* MMC uses open drain drivers in the enumeration phase */
>  static int mmc_host_reset(struct mmc *dev)
> @@ -373,6 +382,7 @@ static const struct mmc_ops arm_pl180_mmci_ops = {
>  	.send_cmd = host_request,
>  	.set_ios = host_set_ios,
>  	.init = mmc_host_reset,
> +	.get_b_max = arm_pl180_get_b_max,
>  };
> 
>  /*
> @@ -531,6 +541,7 @@ static const struct dm_mmc_ops arm_pl180_dm_mmc_ops = {
>  	.send_cmd = dm_host_request,
>  	.set_ios = dm_host_set_ios,
>  	.get_cd = dm_mmc_getcd,
> +	.get_b_max = arm_pl180_get_b_max,
>  };
> 
>  static int arm_pl180_mmc_of_to_plat(struct udevice *dev)
> --
> 2.44.0