RDMA/cma: Use output interface for net_dev check

Commit 27cfde79 ("RDMA/cma: Fix arguments order in net device
validation") swapped the src and dst addresses in the call to
validate_net_dev().

As a consequence, the test in validate_ipv4_net_dev() to see if the
net_dev is the right one, is incorrect for port 1 <-> 2 communication when
the ports are on the same sub-net. This is fixed by denoting the
flowi4_oif as the device instead of the incoming one.

The bug has not been observed using IPv6 addresses.

Fixes: 27cfde79 ("RDMA/cma: Fix arguments order in net device validation")
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Link: https://lore.kernel.org/r/20221012141542.16925-1-haakon.bugge@oracle.comReviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/cma.c

@@ -1556,7 +1556,7 @@ static bool validate_ipv4_net_dev(struct net_device *net_dev,
 		return false;
 
 	memset(&fl4, 0, sizeof(fl4));
-	fl4.flowi4_iif = net_dev->ifindex;
+	fl4.flowi4_oif = net_dev->ifindex;
 	fl4.daddr = daddr;
 	fl4.saddr = saddr;