drivers/mtd/devices/docg3.c: avoid world-writable sysfs files.

In line with practice for module parameters, we're adding a build-time
check that sysfs files aren't world-writable.

Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

drivers/mtd/devices/docg3.c

@@ -1608,8 +1608,8 @@ static ssize_t dps1_insert_key(struct device *dev,
 #define FLOOR_SYSFS(id) { \
 	__ATTR(f##id##_dps0_is_keylocked, S_IRUGO, dps0_is_key_locked, NULL), \
 	__ATTR(f##id##_dps1_is_keylocked, S_IRUGO, dps1_is_key_locked, NULL), \
-	__ATTR(f##id##_dps0_protection_key, S_IWUGO, NULL, dps0_insert_key), \
-	__ATTR(f##id##_dps1_protection_key, S_IWUGO, NULL, dps1_insert_key), \
+	__ATTR(f##id##_dps0_protection_key, S_IWUSR|S_IWGRP, NULL, dps0_insert_key), \
+	__ATTR(f##id##_dps1_protection_key, S_IWUSR|S_IWGRP, NULL, dps1_insert_key), \
 }
 
 static struct device_attribute doc_sys_attrs[DOC_MAX_NBFLOORS][4] = {