sit: check if IPv6 enabled before calling ip6_err_gen_icmpv6_unreach()

liuhangbin · davem330 · commit 173656accaf5 · 2019-02-07T10:48:42.000-08:00
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 <jishi@redhat.com> Fixes: ca15a07 ("sit: generate icmpv6 error when receiving icmpv4 error") Cc: Oussama Ghorbel <ghorbel@pivasoftware.com> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Reviewed-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
@@ -546,7 +546,8 @@ 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)

Original file line number	Diff line number	Diff line change
`@@ -546,7 +546,8 @@ static int ipip6_err(struct sk_buff *skb, u32 info)`
`546`	`546`	`}`
`547`	`547`
`548`	`548`	`err = 0;`
`549`		`- if (!ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len))`
	`549`	`+ if (__in6_dev_get(skb->dev) &&`
	`550`	`+ !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len))`
`550`	`551`	`goto out;`
`551`	`552`
`552`	`553`	`if (t->parms.iph.daddr == 0)`