On Mon, 2 Nov 2015, Chris J Arges wrote:
[...]
> +static int klp_get_func_pos_callback(void *data, const char *name,
> + struct module *mod, unsigned long addr)
> +{
> + struct klp_find_arg *args = data;
> +
> + if ((mod && !args->objname) || (!mod && args->objname))
> + return 0;
> +
> + if (strcmp(args->name, name))
> + return 0;
> +
> + if (args->objname && strcmp(args->objname, mod->name))
> + return 0;
> +
> + /* on address match, return 1 to break kallsyms_on_each_symbol loop */
> + if (args->addr == addr)
> + return 1;
> +
> + /* if we don't match addr, count instance of named symbol */
> + args->count++;
> +
> + return 0;
> +}
> +
> +static int klp_get_func_pos(struct klp_object *obj, struct klp_func *func)
> +{
> + struct klp_find_arg args = {
> + .objname = obj->name,
> + .name = func->old_name,
> + .addr = func->old_addr,
> + .count = 0,
> + };
> +
> + mutex_lock(&module_mutex);
> + kallsyms_on_each_symbol(klp_get_func_pos_callback, &args);
> + mutex_unlock(&module_mutex);
> +
> + return args.count;
> +}
> +
> static int klp_init_func(struct klp_object *obj, struct klp_func *func)
> {
> INIT_LIST_HEAD(&func->stack_node);
> func->state = KLP_DISABLED;
>
> return kobject_init_and_add(&func->kobj, &klp_ktype_func,
> - &obj->kobj, "%s", func->old_name);
> + &obj->kobj, "%s,%d", func->old_name,
> + klp_get_func_pos(obj, func));
> }
There is a problem which I missed before. klp_init_func() is called before
klp_find_verify_func_addr() in klp_init_object(). This means that
func->old_addr is either not verified yet or worse it is still 0. This
means that klp_get_func_pos_callback() never returns 1 and is thus called
on each symbol. So if you for example patched cmdline_proc_show the
resulting directory in sysfs would be called cmdline_proc_show,1 because
addr is never matched. Had old_addr been specified the name would have
been probably correct, but not for sure.
This should be fixed as well.
Miroslav
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