KaFai Wan <[email protected]> writes: > On Mon, 2026-01-05 at 11:46 +0100, Toke Høiland-Jørgensen wrote: >> KaFai Wan <[email protected]> writes: >> >> > This fix reverts to the original version and ensures data_hard_start >> > correctly points to the xdp_frame structure, eliminating the security >> > risk. >> >> This is wrong. We should just be checking the meta_len on input to >> account for the size of xdp_frame. I'll send a patch. > > Current version the actual limit of the max input meta_len for live frames is > XDP_PACKET_HEADROOM - sizeof(struct xdp_frame), not > XDP_PACKET_HEADROOM.
By "current version", you mean the patch I sent[0], right? If so, that was deliberate: the stack limits the maximum data_meta size to XDP_PACKET_HEADROOM - sizeof(struct xdp_frame), so there's no reason not to do the same for bpf_prog_run(). And some chance that diverging here will end up surfacing other bugs down the line. -Toke [0] https://lore.kernel.org/r/[email protected]
