A small detail carried over from the other thread:
>
> but a bigger problem might the following thing:
>
> vscnprintf()
> pointer()
> ptr_to_id()
> initialize_ptr_secret()
> get_random_bytes()
> _get_random_bytes()
> extract_crng()
> _extract_crng()
> spin_lock_irqsave(&crng->lock, flags); <<<<<
>
>
> this, once again, can deadlock. can it? just like before:
So, actually, then, we need to do this as an initcall. Fortunately,
that simplifies things greatly. Here's a rough sketch of what that
looks like, which you'll probably need to debug and refine:
static siphash_key_t ptr_secret __ro_after_init;
static DEFINE_STATIC_KEY_TRUE(no_ptr_secret);
static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec)
{
if (static_branch_unlikely(&no_ptr_secret))
return "(pointer value)";
hashval = ....
}
static void fill_random_ptr_key(struct random_ready_callback *rdy)
{
get_random_bytes(&ptr_secret, sizeof(ptr_secret));
static_branch_disable(&no_ptr_secret);
}
static struct random_ready_callback random_ready = {
.func = fill_random_ptr_key
};
static int __init initialize_ptr_random(void)
{
int ret = add_random_ready_callback(&random_ready);
if (!ret)
return 0;
else if (ret == -EALREADY) {
fill_random_ptr_key(&random_ready);
return 0;
}
return ret;
}
early_initcall(initialize_ptr_random);
