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

Jaehoon Chung
2024-04-15T11:02:01Z

> -----Original Message-----
> From: cmax@mailbox.org <cmax@mailbox.org>
> Sent: Monday, April 15, 2024 6:53 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 | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/mmc/arm_pl180_mmci.c b/drivers/mmc/arm_pl180_mmci.c
> index 2666b65362..cecc7ad783 100644
> --- a/drivers/mmc/arm_pl180_mmci.c
> +++ b/drivers/mmc/arm_pl180_mmci.c
> @@ -229,6 +229,7 @@ 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);
> @@ -356,6 +357,14 @@ 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;
> +}
> +
> static void arm_pl180_mmc_init(struct pl180_mmc_host *host)
> {
> u32 sdi_u32;
> @@ -470,6 +479,7 @@ 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