[PATCH 4.9 22/32] lwtunnel: valid encap attr check should return 0 when lwtunnel is disabled

From: Greg Kroah-Hartman
Date: Thu Feb 16 2017 - 13:02:52 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 2bd137de531367fb573d90150d1872cb2a2095f7 ]

An error was reported upgrading to 4.9.8:
root@Typhoon:~# ip route add default table 210 nexthop dev eth0 via
weight 1 nexthop dev eth0 via weight 1
RTNETLINK answers: Operation not supported

The problem occurs when CONFIG_LWTUNNEL is not enabled and a multipath
route is submitted.

The point of lwtunnel_valid_encap_type_attr is catch modules that
need to be loaded before any references are taken with rntl held. With
CONFIG_LWTUNNEL disabled, there will be no modules to load so the
lwtunnel_valid_encap_type_attr stub should just return 0.

Fixes: 9ed59592e3e3 ("lwtunnel: fix autoload of lwt modules")
Reported-by: pupilla@xxxxxxxxx
Signed-off-by: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
include/net/lwtunnel.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/include/net/lwtunnel.h
+++ b/include/net/lwtunnel.h
@@ -176,7 +176,10 @@ static inline int lwtunnel_valid_encap_t
static inline int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int len)
- return -EOPNOTSUPP;
+ /* return 0 since we are not walking attr looking for
+ * RTA_ENCAP_TYPE attribute on nexthops.
+ */
+ return 0;

static inline int lwtunnel_build_state(struct net_device *dev, u16 encap_type,