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Date: Tue, 17 Jan 2023 16:12:40 +0800
From: Tzung-Bi Shih <tzungbi@kernel.org>
To: bleung@chromium.org, groeck@chromium.org
Cc: chrome-platform@lists.linux.dev, markhas@chromium.org,
	bhanumaiya@chromium.org, error27@gmail.com
Subject: Re: [PATCH] platform/chrome: cros_ec_uart: fix negative type
 promoted to high
Message-ID: <Y8ZYeIev6SR2vMs6@google.com>
References: <20230109081554.3792547-1-tzungbi@kernel.org>
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In-Reply-To: <20230109081554.3792547-1-tzungbi@kernel.org>

On Mon, Jan 09, 2023 at 04:15:54PM +0800, Tzung-Bi Shih wrote:
> 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>
> ---
> Reported in https://lore.kernel.org/chrome-platform/Y7fhw4S7Tb0GcHMF@kili/T/#u.
> 
>  drivers/platform/chrome/cros_ec_uart.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
> index 6916069f1599..788246559bbb 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;
>  	}

Does this patch make sense to someone in the mailing list?