Re: [PATCH] usb: typec: ucsi: Clear PPM capability data in ucsi_init() error path

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On Wed, Jun 09, 2021 at 12:35:35AM -0700, Jack Pham wrote:
> From: Mayank Rana <mrana@xxxxxxxxxxxxxx>
> 
> If ucsi_init() fails for some reason (e.g. ucsi_register_port()
> fails or general communication failure to the PPM), particularly at
> any point after the GET_CAPABILITY command had been issued, this
> results in unwinding the initialization and returning an error.
> However the ucsi structure's ucsi_capability member retains its
> current value, including likely a non-zero num_connectors.
> And because ucsi_init() itself is done in a workqueue a UCSI
> interface driver will be unaware that it failed and may think the
> ucsi_register() call was completely successful.  Later, if
> ucsi_unregister() is called, due to this stale ucsi->cap value it
> would try to access the items in the ucsi->connector array which
> might not be in a proper state or not even allocated at all and
> results in NULL or invalid pointer dereference.
> 
> Fix this by clearing the ucsi->cap value to 0 during the error
> path of ucsi_init() in order to prevent a later ucsi_unregister()
> from entering the connector cleanup loop.
> 
> Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Mayank Rana <mrana@xxxxxxxxxxxxxx>
> Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx>

Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  drivers/usb/typec/ucsi/ucsi.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index b433169ef6fa..b7d104c80d85 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1253,6 +1253,7 @@ static int ucsi_init(struct ucsi *ucsi)
>  	}
>  
>  err_reset:
> +	memset(&ucsi->cap, 0, sizeof(ucsi->cap));
>  	ucsi_reset_ppm(ucsi);
>  err:
>  	return ret;
> -- 
> 2.24.0

-- 
heikki



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