Re: [PATCH 1/2] Revert "udp: Make rport calculation more local"

On Fri, Jun 21, 2024 at 05:53:22PM +0200, Stefano Brivio wrote:

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 Link: https://bugs.passt.top/show_bug.cgi?id=80 Signed-off-by: Stefano Brivio

Argh, dammit. So, Reviewed-by: David Gibson .. but I think we really need to put a comment on this, otherwise one of us is likely to make the same mistake again, because that particular promotion rule is truly arcane.

--- udp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

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; } }

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson