Revert "udp: Make rport calculation more local"

This reverts commit c80fa6a6bb4415ad48f9e11424310875d0d99bc7, as it
reintroduces the issue fixed by commit 1e6f92b995a9 ("udp: Fix 16-bit
overflow in udp_invert_portmap()").

Reported-by: Laurent Jacquot <jk@lutty.net>
Link: https://bugs.passt.top/show_bug.cgi?id=80
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 2 insertions, 1 deletions

diff --git a/udp.c b/udp.c
index e79ca93..8181900 100644
--- a/udp.c
+++ b/udp.c
@@ -279,9 +279,10 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
 		      "Forward and reverse delta arrays must have same size");
 	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
 		in_port_t delta = fwd->f.delta[i];
+		in_port_t rport = i + delta;
 
 		if (delta)
-			fwd->rdelta[i + delta] = NUM_PORTS - delta;
+			fwd->rdelta[rport] = NUM_PORTS - delta;
 	}
 }