RE: [PATCH net v3] i40e: xsk: fix multi-buffer XDP_PASS skb construction

From: Chenguang Zhao <redacted>

When AF_XDP ZC receives a multi-buffer frame and the XDP program
returns XDP_PASS, i40e_construct_skb_zc() copies frags into a new
skb. The copy used skb_frag_page() as the memcpy source (page
metadata instead of packet data) and passed a virtual address to
__skb_fill_page_desc_noacc(), which expects a struct page *.

Use skb_frag_address() for the copy, attach frags with
skb_add_rx_frag() so len/data_len/truesize are updated, and on
dev_alloc_page() failure free the skb via the shared out path so
xsk_buff_free() still runs and previously attached pages are
released by kfree_skb.

Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support")
Signed-off-by: Chenguang Zhao <redacted>
Reviewed-by: Aleksandr Loktionov <redacted>
Reviewed-by: Jason Xing <redacted>

Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>