From 8651be8f14a12d24f203f283601d9b0418c389ff Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Wed, 19 Oct 2016 23:35:12 -0700 Subject: [PATCH] ipv6: fix a potential deadlock in do_ipv6_setsockopt() Baozeng reported this deadlock case: CPU0 CPU1 ---- ---- lock([ 165.136033] sk_lock-AF_INET6); lock([ 165.136033] rtnl_mutex); lock([ 165.136033] sk_lock-AF_INET6); lock([ 165.136033] rtnl_mutex); Similar to commit 87e9f0315952 ("ipv4: fix a potential deadlock in mcast getsockopt() path") this is due to we still have a case, ipv6_sock_mc_close(), where we acquire sk_lock before rtnl_lock. Close this deadlock with the similar solution, that is always acquire rtnl lock first. Fixes: baf606d9c9b1 ("ipv4,ipv6: grab rtnl before locking the socket") Reported-by: Baozeng Ding Tested-by: Baozeng Ding Cc: Marcelo Ricardo Leitner Signed-off-by: Cong Wang Reviewed-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- include/net/addrconf.h | 1 + net/ipv6/ipv6_sockglue.c | 3 ++- net/ipv6/mcast.c | 17 ++++++++++++----- 3 files changed, 15 insertions(+), 6 deletions(-) diff --git a/include/net/addrconf.h b/include/net/addrconf.h index f2d072787947..8f998afc1384 100644 --- a/include/net/addrconf.h +++ b/include/net/addrconf.h @@ -174,6 +174,7 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr); int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr); +void __ipv6_sock_mc_close(struct sock *sk); void ipv6_sock_mc_close(struct sock *sk); bool inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr, const struct in6_addr *src_addr); diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 5330262ab673..636ec56f5f50 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -120,6 +120,7 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk, static bool setsockopt_needs_rtnl(int optname) { switch (optname) { + case IPV6_ADDRFORM: case IPV6_ADD_MEMBERSHIP: case IPV6_DROP_MEMBERSHIP: case IPV6_JOIN_ANYCAST: @@ -198,7 +199,7 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, } fl6_free_socklist(sk); - ipv6_sock_mc_close(sk); + __ipv6_sock_mc_close(sk); /* * Sock is moving from IPv6 to IPv4 (sk_prot), so diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 75c1fc54f188..14a3903f1c82 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -276,16 +276,14 @@ static struct inet6_dev *ip6_mc_find_dev_rcu(struct net *net, return idev; } -void ipv6_sock_mc_close(struct sock *sk) +void __ipv6_sock_mc_close(struct sock *sk) { struct ipv6_pinfo *np = inet6_sk(sk); struct ipv6_mc_socklist *mc_lst; struct net *net = sock_net(sk); - if (!rcu_access_pointer(np->ipv6_mc_list)) - return; + ASSERT_RTNL(); - rtnl_lock(); while ((mc_lst = rtnl_dereference(np->ipv6_mc_list)) != NULL) { struct net_device *dev; @@ -303,8 +301,17 @@ void ipv6_sock_mc_close(struct sock *sk) atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc); kfree_rcu(mc_lst, rcu); - } +} + +void ipv6_sock_mc_close(struct sock *sk) +{ + struct ipv6_pinfo *np = inet6_sk(sk); + + if (!rcu_access_pointer(np->ipv6_mc_list)) + return; + rtnl_lock(); + __ipv6_sock_mc_close(sk); rtnl_unlock(); } -- 2.20.1