[PATCH v3 1/2] usb: typec: tipd: fix uninitialized typec_partner_desc in tps6598x_connect()

[Radhey Shyam Pandey]

tps6598x_connect() passes a stack-allocated typec_partner_desc to
typec_register_partner() after initializing only usb_pd, accessory and
identity.

typec_register_partner() copies attach and deattach from the descriptor
into the partner. With those fields left unset, garbage function pointers
may be stored and later invoked from typec_partner_link_device() when a USB
device is linked to the port. Uninitialized pd_revision and usb_capability
similarly leak stack data through partner sysfs.

Zero-initialize the descriptor so optional callbacks remain NULL and the
remaining fields are zero.

Fixes: 0a4c005bd171 ("usb: typec: driver for TI TPS6598x USB Power Delivery controllers")
Cc: stable@xxxxxxxxxxxxxxx # 5.15+
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx>
---
Changes for v3:
- Split v2 into separate patches to simplify LTS backporting.
- Drop Heikki reviewed-by tag as now patch is split.

Changes for v2:
- Add  Assisted-by tag.
- Remove explicit indentity=NULL

AI code scanning identified this issue; the possible call graph is shown below.

  USB-C plug event (IRQ)
    tps6598x_interrupt()
      tps6598x_handle_plug_event()
        tps6598x_connect()
          struct typec_partner_desc desc;     /* bug: attach/deattach unset */
          desc.usb_pd / .accessory / .identity = ...
          typec_register_partner(port, &desc)   /* class.c */
            partner->attach   = desc->attach;   /* copy stack garbage */
            partner->deattach = desc->deattach;
            [if port->usb2_dev || port->usb3_dev already set]
              typec_partner_link_device(partner, dev)
                if (partner->attach)
                  partner->attach(partner, dev)  /* indirect call via bad ptr */
---
 drivers/usb/typec/tipd/core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
index 522f56742aa9..54ca726c3b15 100644
--- a/drivers/usb/typec/tipd/core.c
+++ b/drivers/usb/typec/tipd/core.c
@@ -344,7 +344,7 @@ static void tps6598x_set_data_role(struct tps6598x *tps,
 
 static int tps6598x_connect(struct tps6598x *tps, u32 status)
 {
-	struct typec_partner_desc desc;
+	struct typec_partner_desc desc = { };
 	enum typec_pwr_opmode mode;
 	int ret;
 
@@ -355,7 +355,6 @@ static int tps6598x_connect(struct tps6598x *tps, u32 status)
 
 	desc.usb_pd = mode == TYPEC_PWR_MODE_PD;
 	desc.accessory = TYPEC_ACCESSORY_NONE; /* XXX: handle accessories */
-	desc.identity = NULL;
 
 	if (desc.usb_pd) {
 		ret = tps6598x_read_partner_identity(tps);
-- 
2.43.0