[PATCH] check for strlen()==0 before accessing strlen()-1

diff --git a/udev_rules.c b/udev_rules.c
index b7905477de8b8dc3531b9dcd24a83ed343bd485b..c07abb9be064b6897c150e095510a5c7ffa196eb 100644 (file)
--- a/udev_rules.c
+++ b/udev_rules.c
@@ -594,15 +594,16 @@ static int match_rule(struct udevice *udev, struct udev_rule *rule,
                        for (i = 0; i < rule->sysfs_pair_count; i++) {
                                struct key_pair *pair;
                                char value[VALUE_SIZE];
+                               size_t len;
 
                                pair = &rule->sysfs_pair[i];
                                if (find_sysfs_attribute(class_dev, parent_device, pair->name, value, sizeof(value)) != 0)
                                        goto try_parent;
 
                                /* strip trailing whitespace of value, if not asked to match for it */
-                               if (!isspace(pair->value[strlen(pair->value)-1])) {
-                                       size_t len = strlen(value);
-
+                               len = strlen(pair->value);
+                               if (len && !isspace(pair->value[len-1])) {
+                                       len = strlen(value);
                                        while (len > 0 && isspace(value[len-1]))
                                                value[--len] = '\0';
                                        dbg("removed %i trailing whitespace chars from '%s'", strlen(value)-len, value);