platform/chrome: cros_ec_proto: handle empty payload in getting proto info

cros_ec_get_proto_info() expects to receive
sizeof(struct ec_response_get_protocol_info) 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_proto_info().

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220609084957.3684698-10-tzungbi@kernel.org

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 1009b8e..a34ef2b 100644 (file)
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -314,6 +314,11 @@ static int cros_ec_get_proto_info(struct cros_ec_device *ec_dev, int devidx)
                goto exit;
        }
 
+       if (ret == 0) {
+               ret = -EPROTO;
+               goto exit;
+       }
+
        info = (struct ec_response_get_protocol_info *)msg->data;
 
        switch (devidx) {