From: Xin Long <lucien.xin@gmail.com>
Date: Fri, 15 Sep 2017 15:58:33 +0800
Subject: ip6_tunnel: do not allow loading ip6_tunnel if ipv6 is disabled in
cmdline
Git-commit: 8c22dab03ad072e45060c299c70d02a4f6fc4aab
Patch-mainline: v4.14-rc2
References: networking-stable-17_10_09
If ipv6 has been disabled from cmdline since kernel started, it makes
no sense to allow users to create any ip6 tunnel. Otherwise, it could
some potential problem.
Jianlin found a kernel crash caused by this in ip6_gre when he set
ipv6.disable=1 in grub:
[ 209.588865] Unable to handle kernel paging request for data at address 0x00000080
[ 209.588872] Faulting instruction address: 0xc000000000a3aa6c
[ 209.588879] Oops: Kernel access of bad area, sig: 11 [#1]
[ 209.589062] NIP [c000000000a3aa6c] fib_rules_lookup+0x4c/0x260
[ 209.589071] LR [c000000000b9ad90] fib6_rule_lookup+0x50/0xb0
[ 209.589076] Call Trace:
[ 209.589097] fib6_rule_lookup+0x50/0xb0
[ 209.589106] rt6_lookup+0xc4/0x110
[ 209.589116] ip6gre_tnl_link_config+0x214/0x2f0 [ip6_gre]
[ 209.589125] ip6gre_newlink+0x138/0x3a0 [ip6_gre]
[ 209.589134] rtnl_newlink+0x798/0xb80
[ 209.589142] rtnetlink_rcv_msg+0xec/0x390
[ 209.589151] netlink_rcv_skb+0x138/0x150
[ 209.589159] rtnetlink_rcv+0x48/0x70
[ 209.589169] netlink_unicast+0x538/0x640
[ 209.589175] netlink_sendmsg+0x40c/0x480
[ 209.589184] ___sys_sendmsg+0x384/0x4e0
[ 209.589194] SyS_sendmsg+0xd4/0x140
[ 209.589201] SyS_socketcall+0x3e0/0x4f0
[ 209.589209] system_call+0x38/0xe0
This patch is to return -EOPNOTSUPP in ip6_tunnel_init if ipv6 has been
disabled from cmdline.
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/ipv6/ip6_tunnel.c | 3 +++
1 file changed, 3 insertions(+)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -2257,6 +2257,9 @@ static int __init ip6_tunnel_init(void)
{
int err;
+ if (!ipv6_mod_enabled())
+ return -EOPNOTSUPP;
+
err = register_pernet_device(&ip6_tnl_net_ops);
if (err < 0)
goto out_pernet;