netlink: fix error handling

Fix netlink_process_msg() to propagate potential error
from netlink_senderr(). Normally netlink_senderr() should return
0 indicating that the error response was built successfully.
This patch tweaks the logic to make sure the error response
in such case is sent back as a NLMSG_ERROR reply accordingly
instead of making sendmsg() return error.

Signed-off-by: Waldemar Kozaczuk <[email protected]>

Author: wkozaczuk

bsd/sys/compat/linux/linux_netlink.cc

@@ -830,7 +830,7 @@ netlink_process_getneigh_msg(struct socket *so, struct nlmsghdr *nlm)
 	struct netlink_getneigh_lle_cbdata cbdata;
 	int error;
 
-	if (nlm->nlmsg_len < sizeof (struct ndmsg)) {
+	if (nlm->nlmsg_len < NLMSG_LENGTH(sizeof (struct ndmsg))) {
 		return EINVAL;
 	}
 
@@ -892,7 +892,7 @@ netlink_process_msg(struct mbuf *m, struct socket *so)
 
 flush:
 	if (error) {
-		netlink_senderr(so, nlm, error);
+		error = netlink_senderr(so, nlm, error);
 	}
 	if (m) {
 		m_freem(m);