[PATCH v2] usb: typec: ucsi: Fix NULL pointer dereference in ucsi_displayport_vdm()

[Ma Ke]

When dp->con->partner is an error, a NULL pointer dereference may occur.
Add a check for dp->con->partner to avoid dereferencing a NULL pointer.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 372adf075a43 ("usb: typec: ucsi: Determine common SVDM Version")
Signed-off-by: Ma Ke <make24@xxxxxxxxxxx>
---
Changes in v2:
- added Cc stable line;
- fixed a typo.
---
 drivers/usb/typec/ucsi/displayport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/typec/ucsi/displayport.c b/drivers/usb/typec/ucsi/displayport.c
index 420af5139c70..ecc706e0800d 100644
--- a/drivers/usb/typec/ucsi/displayport.c
+++ b/drivers/usb/typec/ucsi/displayport.c
@@ -222,6 +222,8 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt,
 	switch (cmd_type) {
 	case CMDT_INIT:
 		if (PD_VDO_SVDM_VER(header) < svdm_version) {
+			if (IS_ERR_OR_NULL(dp->con->partner))
+				break;
 			typec_partner_set_svdm_version(dp->con->partner, PD_VDO_SVDM_VER(header));
 			svdm_version = PD_VDO_SVDM_VER(header);
 		}
-- 
2.25.1