From: Tzung-Bi Shih <tzungbi@kernel.org>
Date: Mon, 9 Jan 2023 08:15:54 +0000 (+0800)
Subject: platform/chrome: cros_ec_uart: fix negative type promoted to high
X-Git-Tag: v6.3-rc1~165^2~6
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8bb233b27fb7c11deefbe2318e75490b22cf3d1a;p=thirdparty%2Fkernel%2Flinux.git

platform/chrome: cros_ec_uart: fix negative type promoted to high

serdev_device_write_buf() returns negative numbers on errors.  When
the return value compares to unsigned integer `len`, it promotes to
quite large positive number.

Fix it.

Fixes: 04a8bdd135cc ("platform/chrome: cros_ec_uart: Add transport layer")
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20230109081554.3792547-1-tzungbi@kernel.org
---

diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
index 6916069f15992..788246559bbba 100644
--- a/drivers/platform/chrome/cros_ec_uart.c
+++ b/drivers/platform/chrome/cros_ec_uart.c
@@ -149,9 +149,10 @@ static int cros_ec_uart_pkt_xfer(struct cros_ec_device *ec_dev,
 	resp->status = 0;
 
 	ret = serdev_device_write_buf(serdev, ec_dev->dout, len);
-	if (ret < len) {
+	if (ret < 0 || ret < len) {
 		dev_err(ec_dev->dev, "Unable to write data\n");
-		ret = -EIO;
+		if (ret >= 0)
+			ret = -EIO;
 		goto exit;
 	}