Check if file object is valid

clamconf/clamconf.c

@@ -232,8 +232,12 @@ static void print_platform(struct cli_environment *env)
     if (!access("/etc/release", R_OK)) {
         char buf[1024];
         FILE *f = fopen("/etc/release", "r");
+
+        if (f) {
             fgets(buf, sizeof(buf), f);
             printf("Full OS version: %s", buf);
+            fclose(f);
+        }
     }
 #endif