Re: XDP invalid memory access

[Vincent Li <mchun.li@xxxxxxxxx>]

On Wed, Jan 15, 2020 at 2:21 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:

> You have to check that you're not reading out of bounds before
> dereferencing the bytes in the TCP header...
>

I have below before the optlen

   47 /* sanity check needed by the eBPF verifier */

    48 if ((void *)(tcphdr + 1) > data_end)

    49 return 0;

this is not enough, how do I check the out of bounds properly?

Regards,

Vincent