From 2b0925f939cbf8e74f6c342fc0eedf45ade967c8 Mon Sep 17 00:00:00 2001 From: Hangbin Liu Date: Thu, 7 Feb 2019 18:36:11 +0800 Subject: [PATCH] sit: check if IPv6 enabled before calling ip6_err_gen_icmpv6_unreach() [ Upstream commit 173656accaf583698bac3f9e269884ba60d51ef4 ] If we disabled IPv6 from the kernel command line (ipv6.disable=1), we should not call ip6_err_gen_icmpv6_unreach(). This: ip link add sit1 type sit local 192.0.2.1 remote 192.0.2.2 ttl 1 ip link set sit1 up ip addr add 198.51.100.1/24 dev sit1 ping 198.51.100.2 if IPv6 is disabled at boot time, will crash the kernel. v2: there's no need to use in6_dev_get(), use __in6_dev_get() instead, as we only need to check that idev exists and we are under rcu_read_lock() (from netif_receive_skb_internal()). Reported-by: Jianlin Shi Fixes: ca15a078bd90 ("sit: generate icmpv6 error when receiving icmpv4 error") Cc: Oussama Ghorbel Signed-off-by: Hangbin Liu Reviewed-by: Stefano Brivio Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/sit.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index fc7ca1e..4381ea5 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -540,7 +540,8 @@ static int ipip6_err(struct sk_buff *skb, u32 info) } err = 0; - if (!ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len)) + if (__in6_dev_get(skb->dev) && + !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len)) goto out; if (t->parms.iph.daddr == 0) -- 2.7.4