[PATCH 4.9 145/177] cros_ec: fix nul-termination for firmware build info

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>


[ Upstream commit 50a0d71a5d20e1d3eff1d974fdc8559ad6d74892 ]

As gcc-8 reports, we zero out the wrong byte:

drivers/platform/chrome/cros_ec_sysfs.c: In function 'show_ec_version':
drivers/platform/chrome/cros_ec_sysfs.c:190:12: error: array subscript 4294967295 is above array bounds of 'uint8_t[]' [-Werror=array-bounds]

This changes the code back to what it did before changing to a
zero-length array structure.

Fixes: a841178445bb ("mfd: cros_ec: Use a zero-length array for command data")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Benson Leung <bleung@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/platform/chrome/cros_ec_sysfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/platform/chrome/cros_ec_sysfs.c
+++ b/drivers/platform/chrome/cros_ec_sysfs.c
@@ -187,7 +187,7 @@ static ssize_t show_ec_version(struct de
 		count += scnprintf(buf + count, PAGE_SIZE - count,
 				   "Build info:    EC error %d\n", msg->result);
 	else {
-		msg->data[sizeof(msg->data) - 1] = '\0';
+		msg->data[EC_HOST_PARAM_SIZE - 1] = '\0';
 		count += scnprintf(buf + count, PAGE_SIZE - count,
 				   "Build info:    %s\n", msg->data);
 	}