[PATCH] mfd: cros_ec_dev: Don't advertise junk features on failure

[PATCH] mfd: cros_ec_dev: Don't advertise junk features on failure

[Stephen Boyd]

If the feature query fails during this driver's probe, we memset the
features bits to 0, but then we continue to overwrite that with whatever
junk we read back when the feature probing failed. In the case of a SPI
device, it may be complete junk, causing the caller of this function to
think certain features are present when they aren't. Don't copy over the
bad message on failure so we can fail more gracefully.

Fixes: e4244ebddae2 ("platform/chrome: Introduce a new function to check EC features.")
Cc: Benson Leung <bleung@chromium.org>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/mfd/cros_ec_dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 1d6dc5c7a19d..d37c79426c87 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -113,10 +113,10 @@ static int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
 			dev_warn(ec->dev, "cannot get EC features: %d/%d\n",
 				 ret, msg->result);
 			memset(ec->features, 0, sizeof(ec->features));
+		} else {
+			memcpy(ec->features, msg->data, sizeof(ec->features));
 		}
 
-		memcpy(ec->features, msg->data, sizeof(ec->features));
-
 		dev_dbg(ec->dev, "EC features %08x %08x\n",
 			ec->features[0], ec->features[1]);
 
-- 
Sent by a computer through tubes

Re: [PATCH] mfd: cros_ec_dev: Don't advertise junk features on failure

[Benson Leung]

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Hi Stephen,

On Wed, May 30, 2018 at 11:23:43PM -0700, Stephen Boyd wrote:
> If the feature query fails during this driver's probe, we memset the
> features bits to 0, but then we continue to overwrite that with whatever
> junk we read back when the feature probing failed. In the case of a SPI
> device, it may be complete junk, causing the caller of this function to
> think certain features are present when they aren't. Don't copy over the
> bad message on failure so we can fail more gracefully.
> 
> Fixes: e4244ebddae2 ("platform/chrome: Introduce a new function to check EC features.")
> Cc: Benson Leung <bleung@chromium.org>
> Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Cc: Gwendal Grignou <gwendal@chromium.org>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>

Acked-by: Benson Leung <bleung@chromium.org>

> ---
>  drivers/mfd/cros_ec_dev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 1d6dc5c7a19d..d37c79426c87 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -113,10 +113,10 @@ static int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
>  			dev_warn(ec->dev, "cannot get EC features: %d/%d\n",
>  				 ret, msg->result);
>  			memset(ec->features, 0, sizeof(ec->features));
> +		} else {
> +			memcpy(ec->features, msg->data, sizeof(ec->features));
>  		}
>  
> -		memcpy(ec->features, msg->data, sizeof(ec->features));
> -
>  		dev_dbg(ec->dev, "EC features %08x %08x\n",
>  			ec->features[0], ec->features[1]);
>  
> -- 
> Sent by a computer through tubes
> 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org

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Re: [PATCH] mfd: cros_ec_dev: Don't advertise junk features on failure

[Lee Jones]

On Wed, 30 May 2018, Stephen Boyd wrote:

> If the feature query fails during this driver's probe, we memset the
> features bits to 0, but then we continue to overwrite that with whatever
> junk we read back when the feature probing failed. In the case of a SPI
> device, it may be complete junk, causing the caller of this function to
> think certain features are present when they aren't. Don't copy over the
> bad message on failure so we can fail more gracefully.
> 
> Fixes: e4244ebddae2 ("platform/chrome: Introduce a new function to check EC features.")
> Cc: Benson Leung <bleung@chromium.org>
> Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Cc: Gwendal Grignou <gwendal@chromium.org>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
>  drivers/mfd/cros_ec_dev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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