usb: typec: tcpm: Check for port partner validity before consuming it

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: [email protected]
Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
Signed-off-by: Badhri Jagan Sridharan <[email protected]>
Reviewed-by: Heikki Krogerus <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 53c1f308ebd7ce98919e6f36fbae6af2f2fa466e..8a1af08f71b6450710e4ae7ff2e891f490a036ca 100644 (file)
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1584,7 +1584,8 @@ static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
        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),
@@ -1746,6 +1747,9 @@ static void tcpm_register_partner_altmodes(struct tcpm_port *port)
        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]);
@@ -4238,7 +4242,10 @@ static int tcpm_init_vconn(struct tcpm_port *port)
 
 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;
@@ -4248,9 +4255,13 @@ static void tcpm_typec_connect(struct tcpm_port *port)
                        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);
        }
 }
@@ -4330,9 +4341,11 @@ static void tcpm_typec_disconnect(struct tcpm_port *port)
        port->plug_prime = NULL;
        port->cable = NULL;
        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;
        }
 }
@@ -4556,6 +4569,9 @@ static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
 
 static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
 {
+       if (!port->partner)
+               return;
+
        switch (port->negotiated_rev) {
        case PD_REV30:
                break;