Hi XDPeople! I've been having great success with reading data from fixed offsets in a packet/ethernet frame. But every time I try to read from a dynamic offset (e.g. read the last byte in the packet by using the packet length in the IP/UDP headers). It looks like once I add a register to a packet pointer, the range is reset to 0, and no amount of comparisons will restore a range. Looking through the verifier code, I believe I found where the range is getting set to 0 (https://elixir.bootlin.com/linux/latest/source/kernel/bpf/verifier.c#L2695), and it looks like the risk of overflow (https://elixir.bootlin.com/linux/latest/source/kernel/bpf/verifier.c#L3267) is why the range doesn't get updated by later comparisons. Is there a way to do a read from a packet at a dynamic offset? If not, is that something that could potentially be added to the verifier? It feels like `if (packet_start <= packet_start + offset && packet_end > packet_start + offset)` is something that should be verifiable as safe, even with potential overflow in `packet_start + offset`? Thank you! --Zvi
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