[PATCH 5.15.y 2/3] ipv6: icmp6: add drop reason support to ndisc_rcv()

[Sasha Levin <sashal@kernel.org>]

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 545dbcd124b02c9dc93c8a5894c71d682effc3e6 ]

Creates three new drop reasons:

SKB_DROP_REASON_IPV6_NDISC_FRAG: invalid frag (suppress_frag_ndisc).

SKB_DROP_REASON_IPV6_NDISC_HOP_LIMIT: invalid hop limit.

SKB_DROP_REASON_IPV6_NDISC_BAD_CODE: invalid NDISC icmp6 code.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

[ sashal: Reduced backport -- upstream 545dbcd124b02 touches 4 file(s), this
  backport carries 1. Not backported here:
  include/net/dropreason.h
  include/net/ndisc.h
  net/ipv6/icmp.c
  net/ipv6/ndisc.c
  This note is generated from the file lists only; see the resolution record
  for the reasoning. ]

Stable-dep-of: f826df95332c ("ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv6/exthdrs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 6111fe395ff09..1a9e2f989734c 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -495,9 +495,9 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 	struct net *net = dev_net(skb->dev);
 	struct inet6_dev *idev;
 	struct ipv6hdr *oldhdr;
-	struct in6_addr addr;
 	unsigned int chdr_len;
 	unsigned char *buf;
+	struct in6_addr addr;
 	int accept_rpl_seg;
 	int i, err;
 	u64 n = 0;
@@ -507,7 +507,6 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 
 	accept_rpl_seg = min(READ_ONCE(net->ipv6.devconf_all->rpl_seg_enabled),
 			     READ_ONCE(idev->cnf.rpl_seg_enabled));
-
 	if (!accept_rpl_seg) {
 		kfree_skb(skb);
 		return -1;
-- 
2.53.0