queue-4.4/sit-check-if-ipv6-enabled-before-calling-ip6_err_gen_icmpv6_unreach.patch

   1 From foo@baz Sun Feb 24 14:41:29 CET 2019
   2 From: Hangbin Liu <liuhangbin@gmail.com>
   3 Date: Thu, 7 Feb 2019 18:36:11 +0800
   4 Subject: sit: check if IPv6 enabled before calling ip6_err_gen_icmpv6_unreach()
   5
   6 From: Hangbin Liu <liuhangbin@gmail.com>
   7
   8 [ Upstream commit 173656accaf583698bac3f9e269884ba60d51ef4 ]
   9
  10 If we disabled IPv6 from the kernel command line (ipv6.disable=1), we should
  11 not call ip6_err_gen_icmpv6_unreach(). This:
  12
  13   ip link add sit1 type sit local 192.0.2.1 remote 192.0.2.2 ttl 1
  14   ip link set sit1 up
  15   ip addr add 198.51.100.1/24 dev sit1
  16   ping 198.51.100.2
  17
  18 if IPv6 is disabled at boot time, will crash the kernel.
  19
  20 v2: there's no need to use in6_dev_get(), use __in6_dev_get() instead,
  21     as we only need to check that idev exists and we are under
  22     rcu_read_lock() (from netif_receive_skb_internal()).
  23
  24 Reported-by: Jianlin Shi <jishi@redhat.com>
  25 Fixes: ca15a078bd90 ("sit: generate icmpv6 error when receiving icmpv4 error")
  26 Cc: Oussama Ghorbel <ghorbel@pivasoftware.com>
  27 Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
  28 Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
  29 Signed-off-by: David S. Miller <davem@davemloft.net>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31 ---
  32  net/ipv6/sit.c |    2 +-
  33  1 file changed, 1 insertion(+), 1 deletion(-)
  34
  35 --- a/net/ipv6/sit.c
  36 +++ b/net/ipv6/sit.c
  37 @@ -577,7 +577,7 @@ static int ipip6_err(struct sk_buff *skb
  38                 goto out;
  39
  40         err = 0;
  41 -       if (!ipip6_err_gen_icmpv6_unreach(skb))
  42 +       if (__in6_dev_get(skb->dev) && !ipip6_err_gen_icmpv6_unreach(skb))
  43                 goto out;
  44
  45         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)