On Fri, Aug 16, 2024 at 6:59 AM Heikki Krogerus
<heikki.krogerus@xxxxxxxxxxxxxxx> wrote:
>
> That may silently corrupt the data. Instead, failing attempts
> to read more than the interface can handle.
>
> Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/typec/ucsi/ucsi.c | 8 ++------
> drivers/usb/typec/ucsi/ucsi.h | 2 ++
> 2 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 4039851551c1..96ef099a6f84 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -99,12 +99,8 @@ static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
>
> *cci = 0;
>
> - /*
> - * Below UCSI 2.0, MESSAGE_IN was limited to 16 bytes. Truncate the
> - * reads here.
> - */
> - if (ucsi->version <= UCSI_VERSION_1_2)
> - size = clamp(size, 0, 16);
> + if (size > UCSI_MAX_DATA_LENGTH(ucsi))
> + return -EINVAL;
>
> ret = ucsi->ops->sync_control(ucsi, command);
> if (ret)
> diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> index 7bc132b59027..5e3c6cb822c8 100644
> --- a/drivers/usb/typec/ucsi/ucsi.h
> +++ b/drivers/usb/typec/ucsi/ucsi.h
> @@ -412,6 +412,8 @@ struct ucsi {
> #define UCSI_DELAY_DEVICE_PDOS BIT(1) /* Reading PDOs fails until the parter is in PD mode */
> };
>
> +#define UCSI_MAX_DATA_LENGTH(u) (((u)->version < UCSI_VERSION_2_0) ? 0x10 : 0xff)
> +
> #define UCSI_MAX_SVID 5
> #define UCSI_MAX_ALTMODES (UCSI_MAX_SVID * 6)
>
> --
> 2.43.0
>
>
Looking through the list of commands that changed between UCSI1.2 and
UCSI2+, only GET_CONNECTOR_STATUS seems to have a size that exceeds 16
bytes (128 bits). As long as we treat that structure specially, this
change should be fine.
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
