[LTP] [RFC PATCH 2/9] lib: Add a canary for guarded buffers

[Li Wang]

On Thu, Aug 1, 2019 at 5:26 PM Cyril Hrubis <chrubis@suse.cz> wrote:
>
> In a case that the buffer size is not a multiple of a page size there is
> unused space before the start of the buffer. Let's fill that with
> center mirrored random bytes and check that the buffer wasn't modified
> before we unmap it.

I like this check canary part. Amazing to me.

> +
> +static void check_canary(struct map *map)
> +{
> +       size_t i;
> +       char *buf = map->addr;
> +
> +       for (i = 0; i < map->buf_shift/2; i++) {
> +               if (buf[map->buf_shift - i - 1] != buf[i]) {
> +                       tst_res(TWARN,
> +                               "pid %i: buffer modified before address %p %zu",
> +                               (char*)map->addr + map->buf_shift, i);

Here you probably missed the getpid() for printing %i match :).

-- 
Regards,
Li Wang