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

[Amit Sunil Dhamne]

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@xxxxxxxxxxxxxxx
Signed-off-by: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
---
 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