platform/chrome: cros_ec_proto: handle empty payload in getting wake mask

cros_ec_get_host_event_wake_mask() expects to receive
sizeof(struct ec_response_host_event_mask) from send_command().  The
payload is valid only if the return value is positive.

Return -EPROTO if send_command() returns 0 in
cros_ec_get_host_event_wake_mask().

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220609084957.3684698-22-tzungbi@kernel.org

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index a7d807c..1bd5672 100644 (file)
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -256,19 +256,23 @@ static int cros_ec_get_host_event_wake_mask(struct cros_ec_device *ec_dev, uint3
        msg->insize = sizeof(*r);
 
        ret = send_command(ec_dev, msg);
-       if (ret >= 0) {
-               mapped = cros_ec_map_error(msg->result);
-               if (mapped) {
-                       ret = mapped;
-                       goto exit;
-               }
+       if (ret < 0)
+               goto exit;
+
+       mapped = cros_ec_map_error(msg->result);
+       if (mapped) {
+               ret = mapped;
+               goto exit;
        }
-       if (ret > 0) {
-               r = (struct ec_response_host_event_mask *)msg->data;
-               *mask = r->mask;
-               ret = 0;
+
+       if (ret == 0) {
+               ret = -EPROTO;
+               goto exit;
        }
 
+       r = (struct ec_response_host_event_mask *)msg->data;
+       *mask = r->mask;
+       ret = 0;
 exit:
        kfree(msg);
        return ret;