[PATCH v4 09/21] platform/chrome: cros_ec_proto: handle empty payload in getting proto info

[Tzung-Bi Shih <tzungbi@kernel.org>]

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>
---
Changes from v3:
- Add R-b tag.

Changes from v2:
- Separate Kunit test to another patch.

 drivers/platform/chrome/cros_ec_proto.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 893b76703da6..6f5be9e5ede4 100644
--- 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) {
-- 
2.36.1.255.ge46751e96f-goog