[PATCH 4.19 09/21] ipv6: Check attribute length for RTA_GATEWAY when deleting multipath route

[Greg Kroah-Hartman]

From: David Ahern <dsahern@xxxxxxxxxx>

commit 1ff15a710a862db1101b97810af14aedc835a86a upstream.

Make sure RTA_GATEWAY for IPv6 multipath route has enough bytes to hold
an IPv6 address.

Fixes: 6b9ea5a64ed5 ("ipv6: fix multipath route replace error recovery")
Signed-off-by: David Ahern <dsahern@xxxxxxxxxx>
Cc: Roopa Prabhu <roopa@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv6/route.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4606,7 +4606,11 @@ static int ip6_route_multipath_del(struc
 
 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 			if (nla) {
-				nla_memcpy(&r_cfg.fc_gateway, nla, 16);
+				err = fib6_gw_from_attr(&r_cfg.fc_gateway, nla,
+							extack);
+				if (err)
+					return err;
+
 				r_cfg.fc_flags |= RTF_GATEWAY;
 			}
 		}