Hello Guillaume, On 2016/11/17 5:07, Guillaume Nault wrote: > On Wed, Nov 16, 2016 at 11:08:23AM -0800, Cong Wang wrote: >> On Wed, Nov 16, 2016 at 8:30 AM, Guillaume Nault <g.na...@alphalink.fr> >> wrote: >>> diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c >>> index fce25af..982f6c4 100644 >>> --- a/net/l2tp/l2tp_ip.c >>> +++ b/net/l2tp/l2tp_ip.c >>> @@ -251,8 +251,6 @@ static int l2tp_ip_bind(struct sock *sk, struct >>> sockaddr *uaddr, int addr_len) >>> int ret; >>> int chk_addr_ret; >>> >>> - if (!sock_flag(sk, SOCK_ZAPPED)) >>> - return -EINVAL; >>> if (addr_len < sizeof(struct sockaddr_l2tpip)) >>> return -EINVAL; >>> if (addr->l2tp_family != AF_INET) >>> @@ -267,6 +265,9 @@ static int l2tp_ip_bind(struct sock *sk, struct >>> sockaddr *uaddr, int addr_len) >>> read_unlock_bh(&l2tp_ip_lock); >>> >>> lock_sock(sk); >>> + if (!sock_flag(sk, SOCK_ZAPPED)) >>> + goto out; >>> + >>> if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct >>> sockaddr_l2tpip)) >>> goto out; >>> >>> diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c >>> index ad3468c..9978d01 100644 >>> --- a/net/l2tp/l2tp_ip6.c >>> +++ b/net/l2tp/l2tp_ip6.c >>> @@ -269,8 +269,6 @@ static int l2tp_ip6_bind(struct sock *sk, struct >>> sockaddr *uaddr, int addr_len) >>> int addr_type; >>> int err; >>> >>> - if (!sock_flag(sk, SOCK_ZAPPED)) >>> - return -EINVAL; >>> if (addr->l2tp_family != AF_INET6) >>> return -EINVAL; >>> if (addr_len < sizeof(*addr)) >>> @@ -296,6 +294,9 @@ static int l2tp_ip6_bind(struct sock *sk, struct >>> sockaddr *uaddr, int addr_len) >>> lock_sock(sk); >>> >>> err = -EINVAL; >>> + if (!sock_flag(sk, SOCK_ZAPPED)) >>> + goto out_unlock; >>> + >>> if (sk->sk_state != TCP_CLOSE) >>> goto out_unlock; >> >> >> Makes sense, it should prevent a concurrent caller adding the socket >> into bind table >> twice after passing __l2tp_ip_bind_lookup() check. > > Yes, and the __l2tp_ip_bind_lookup() call is also racy. But, by > properly checking the SOCK_ZAPPED flag, we probably can remove this > call entirely. > > For now, I only wanted to make sure the issue was well identified. I'll > submit a more complete patch for net (with protected SOCK_ZAPPED check > in l2tp_ip_connect() too). > The patch fixes the issues both for l2tp_ip and l2tp_ip6
Tested-by: Baozeng Ding <splovi...@gmail.com> Best Regards, Baozeng Ding
