[PATCH 6.8 258/336] usb: typec: tcpm: Check for port partner validity before consuming it

Greg Kroah-Hartman
2024-05-14T10:48:12Z

From: Badhri Jagan Sridharan <badhri@google.com>

commit ae11f04b452b5205536e1c02d31f8045eba249dd upstream.

typec_register_partner() does not guarantee partner registration
to always succeed. In the event of failure, port->partner is set
to the error value or NULL. Given that port->partner validity is
not checked, this results in the following crash:

Unable to handle kernel NULL pointer dereference at virtual address xx
pc : run_state_machine+0x1bc8/0x1c08
lr : run_state_machine+0x1b90/0x1c08
..
Call trace:
run_state_machine+0x1bc8/0x1c08
tcpm_state_machine_work+0x94/0xe4
kthread_worker_fn+0x118/0x328
kthread+0x1d0/0x23c
ret_from_fork+0x10/0x20

To prevent the crash, check for port->partner validity before
derefencing it in all the call sites.

Cc: stable@vger.kernel.org
Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240427202812.3435268-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/typec/tcpm/tcpm.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)

--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1501,7 +1501,8 @@ static void svdm_consume_identity(struct
port->partner_ident.cert_stat = p[VDO_INDEX_CSTAT];
port->partner_ident.product = product;

- typec_partner_set_identity(port->partner);
+ if (port->partner)
+ typec_partner_set_identity(port->partner);

tcpm_log(port, "Identity: %04x:%04x.%04x",
PD_IDH_VID(vdo),
@@ -1589,6 +1590,9 @@ static void tcpm_register_partner_altmod
struct typec_altmode *altmode;
int i;

+ if (!port->partner)
+ return;
+
for (i = 0; i < modep->altmodes; i++) {
altmode = typec_partner_register_altmode(port->partner,
&modep->altmode_desc[i]);
@@ -3587,7 +3591,10 @@ static int tcpm_init_vconn(struct tcpm_p

static void tcpm_typec_connect(struct tcpm_port *port)
{
+ struct typec_partner *partner;
+
if (!port->connected) {
+ port->connected = true;
/* Make sure we don't report stale identity information */
memset(&port->partner_ident, 0, sizeof(port->partner_ident));
port->partner_desc.usb_pd = port->pd_capable;
@@ -3597,9 +3604,13 @@ static void tcpm_typec_connect(struct tc
port->partner_desc.accessory = TYPEC_ACCESSORY_AUDIO;
else
port->partner_desc.accessory = TYPEC_ACCESSORY_NONE;
- port->partner = typec_register_partner(port->typec_port,
- &port->partner_desc);
- port->connected = true;
+ partner = typec_register_partner(port->typec_port, &port->partner_desc);
+ if (IS_ERR(partner)) {
+ dev_err(port->dev, "Failed to register partner (%ld)\n", PTR_ERR(partner));
+ return;
+ }
+
+ port->partner = partner;
typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
}
}
@@ -3669,9 +3680,11 @@ out_disable_mux:
static void tcpm_typec_disconnect(struct tcpm_port *port)
{
if (port->connected) {
- typec_partner_set_usb_power_delivery(port->partner, NULL);
- typec_unregister_partner(port->partner);
- port->partner = NULL;
+ if (port->partner) {
+ typec_partner_set_usb_power_delivery(port->partner, NULL);
+ typec_unregister_partner(port->partner);
+ port->partner = NULL;
+ }
port->connected = false;
}
}
@@ -3887,6 +3900,9 @@ static enum typec_cc_status tcpm_pwr_opm

static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
{
+ if (!port->partner)
+ return;
+
switch (port->negotiated_rev) {
case PD_REV30:
break;