Re: [RFC PATCH bpf-next 10/11] bpf: Introduce PTR_ITER and PTR_ITER_END type flags

[Alexei Starovoitov <ast@xxxxxx>]

On 7/22/22 11:34 AM, Dave Marchevsky wrote:
>   	if (__is_pointer_value(false, reg)) {
> +		if (__is_iter_end(reg) && val == 0) {
> +			__mark_reg_const_zero(reg);
> +			switch (opcode) {
> +			case BPF_JEQ:
> +				return 1;
> +			case BPF_JNE:
> +				return 0;
> +			default:
> +				return -1;
> +			}
> +		}

as discussed the verifying the loop twice is not safe.
This needs more advanced verifier hacking.
Maybe let's postpone rbtree iters for now and resolve all the rest?
Or do iters with a callback, since that's more or less a clear path fwd?