samples/bpf: fix xdpsock l2fwd tx for unaligned mode

Preserve the offset of the address of the received descriptor, and include
it in the address set for the tx descriptor, so the kernel can correctly
locate the start of the packet data.

Fixes: 03895e63ff97 ("samples/bpf: add buffer recycling for unaligned chunks to xdpsock")
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index 102eace229568e38e7ff1a64adebdb9152194a8e..df011ac3340222236c25a7ad4f17a07cc316c9ee 100644 (file)
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -685,7 +685,7 @@ static void l2fwd(struct xsk_socket_info *xsk, struct pollfd *fds)
        for (i = 0; i < rcvd; i++) {
                u64 addr = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx)->addr;
                u32 len = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx++)->len;
-               u64 orig = xsk_umem__extract_addr(addr);
+               u64 orig = addr;
 
                addr = xsk_umem__add_offset_to_addr(addr);
                char *pkt = xsk_umem__get_data(xsk->umem->buffer, addr);