Re: [PATCH v1] usb: typec: tcpm: fix use-after-free case in tcpm_register_source_caps

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

On Tue, May 14, 2024 at 03:01:31PM -0700, Amit Sunil Dhamne wrote:
> There could be a potential use-after-free case in
> tcpm_register_source_caps(). This could happen when:
>  * new (say invalid) source caps are advertised
>  * the existing source caps are unregistered
>  * tcpm_register_source_caps() returns with an error as
>    usb_power_delivery_register_capabilities() fails
> 
> This causes port->partner_source_caps to hold on to the now freed source
> caps.
> 
> Reset port->partner_source_caps value to NULL after unregistering
> existing source caps.
> 
> Fixes: 230ecdf71a64 ("usb: typec: tcpm: unregister existing source caps before re-registration")
> Cc: stable@vger.kernel.org
> Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>

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

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 8a1af08f71b6..be4127ef84e9 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -3014,8 +3014,10 @@ static int tcpm_register_source_caps(struct tcpm_port *port)
>  	memcpy(caps.pdo, port->source_caps, sizeof(u32) * port->nr_source_caps);
>  	caps.role = TYPEC_SOURCE;
>  
> -	if (cap)
> +	if (cap) {
>  		usb_power_delivery_unregister_capabilities(cap);
> +		port->partner_source_caps = NULL;
> +	}
>  
>  	cap = usb_power_delivery_register_capabilities(port->partner_pd, &caps);
>  	if (IS_ERR(cap))
> 
> base-commit: 51474ab44abf907023a8a875e799b07de461e466
> -- 
> 2.45.0.rc1.225.g2a3ae87e7f-goog

-- 
heikki