Re: [PATCH] usb: typec: fix potential out of bounds in ucsi_ccg_update_set_new_cam_cmd()

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Mon, Nov 04, 2024 at 08:16:42PM +0300, Dan Carpenter wrote:
> The "*cmd" variable can be controlled by the user via debugfs.  That means
> "new_cam" can be as high as 255 while the size of the uc->updated[] array
> is UCSI_MAX_ALTMODES (30).
> 
> The call tree is:
> ucsi_cmd() // val comes from simple_attr_write_xsigned()
> -> ucsi_send_command()
>    -> ucsi_send_command_common()
>       -> ucsi_run_command() // calls ucsi->ops->sync_control()
>          -> ucsi_ccg_sync_control()
> 
> Fixes: 170a6726d0e2 ("usb: typec: ucsi: add support for separate DP altmode devices")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/usb/typec/ucsi/ucsi_ccg.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
> index ba58d11907bc..bccfc03b5986 100644
> --- a/drivers/usb/typec/ucsi/ucsi_ccg.c
> +++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
> @@ -482,6 +482,8 @@ static void ucsi_ccg_update_set_new_cam_cmd(struct ucsi_ccg *uc,
>  
>  	port = uc->orig;
>  	new_cam = UCSI_SET_NEW_CAM_GET_AM(*cmd);
> +	if (new_cam >= ARRAY_SIZE(uc->updated))
> +		return;
>  	new_port = &uc->updated[new_cam];
>  	cam = new_port->linked_idx;
>  	enter_new_mode = UCSI_SET_NEW_CAM_ENTER(*cmd);
> -- 
> 2.45.2

-- 
heikki