On Tue, Aug 26, 2025 at 6:20 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote: > > On Mon, 25 Aug 2025 22:12:21 -0700 Amery Hung wrote: > > > > + data_end = xdp->data + len; > > > > + delta = data_end - xdp->data_end; > > > > + > > > > + if (delta <= 0) > > > > + return 0; > > > > + > > > > + if (unlikely(data_end > data_hard_end)) > > > > + return -EINVAL; > > > > > > Is this safe against pointers wrapping on 32b systems? > > > > > > > You are right. This may be a problem. > > > > > Maybe it's better to do: > > > > > > if (unlikely(data_hard_end - xdp->data_end < delta)) > > > > > > ? > > > > But delta may be negative if the pointer wraps around and then the > > function will still continue. How about adding data_end < xdp->data > > check and reorganizing the checks like this? > > You already checked that delta is positive in the previous if (), > so I think it's safe. Admittedly having 3 separate conditions is > more readable but it's not strictly necessary. Up to you. Got it. I will change to the new set of checks. The original kfunc would return 0 when pointer wrapping happens and delta <= 0.
