[PATCH 4.9 093/171] ipv6: fix cleanup ordering for ip6_mr failure

Greg Kroah-Hartman
2018-11-08T21:51:03Z

[ Upstream commit afe49de44c27a89e8e9631c44b5ffadf6ace65e2 ]

Commit 15e668070a64 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
moved the cleanup label for ipmr_fail, but should have changed the
contents of the cleanup labels as well. Now we can end up cleaning up
icmpv6 even though it hasn't been initialized (jump to icmp_fail or
ipmr_fail).

Simply undo things in the reverse order of their initialization.

Example of panic (triggered by faking a failure of icmpv6_init):

kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI
[...]
RIP: 0010:__list_del_entry_valid+0x79/0x160
[...]
Call Trace:
? lock_release+0x8a0/0x8a0
unregister_pernet_operations+0xd4/0x560
? ops_free_list+0x480/0x480
? down_write+0x91/0x130
? unregister_pernet_subsys+0x15/0x30
? down_read+0x1b0/0x1b0
? up_read+0x110/0x110
? kmem_cache_create_usercopy+0x1b4/0x240
unregister_pernet_subsys+0x1d/0x30
icmpv6_cleanup+0x1d/0x30
inet6_init+0x1b5/0x23f

Fixes: 15e668070a64 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv6/af_inet6.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 421379014995..f7b425615c12 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -1045,11 +1045,11 @@ netfilter_fail:
igmp_fail:
ndisc_cleanup();
ndisc_fail:
- ip6_mr_cleanup();
+ icmpv6_cleanup();
icmp_fail:
- unregister_pernet_subsys(&inet6_net_ops);
+ ip6_mr_cleanup();
ipmr_fail:
- icmpv6_cleanup();
+ unregister_pernet_subsys(&inet6_net_ops);
register_pernet_fail:
sock_unregister(PF_INET6);
rtnl_unregister_all(PF_INET6);
--
2.17.1