FAILED: patch "[PATCH] ipv6: Check attribute length for RTA_GATEWAY when deleting" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1ff15a710a862db1101b97810af14aedc835a86a Mon Sep 17 00:00:00 2001
From: David Ahern <[email protected]>
Date: Thu, 30 Dec 2021 17:36:34 -0700
Subject: [PATCH] ipv6: Check attribute length for RTA_GATEWAY when deleting
multipath route

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

index d16599c225b8..b311c0bc9983 100644
@@ -5453,7 +5453,11 @@ static int ip6_route_multipath_del(struct fib6_config *cfg,
 
 			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;
 			}
 		}