tipc: fix race between poll() and setsockopt()
Letting tipc_poll() dereference a socket's pointer to struct tipc_group entails a race risk, as the group item may be deleted in a concurrent tipc_sk_join() or tipc_sk_leave() thread. We now move the 'open' flag in struct tipc_group to struct tipc_sock, and let the former retain only a pointer to the moved field. This will eliminate the race risk. Reported-by: syzbot+799dafde0286795858ac@syzkaller.appspotmail.com Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -93,26 +93,21 @@ struct tipc_group {
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u16 max_active;
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u16 bc_snd_nxt;
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u16 bc_ackers;
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bool *open;
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bool loopback;
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bool events;
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bool open;
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};
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static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
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int mtyp, struct sk_buff_head *xmitq);
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bool tipc_group_is_open(struct tipc_group *grp)
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{
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return grp->open;
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}
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static void tipc_group_open(struct tipc_member *m, bool *wakeup)
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{
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*wakeup = false;
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if (list_empty(&m->small_win))
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return;
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list_del_init(&m->small_win);
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m->group->open = true;
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*m->group->open = true;
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*wakeup = true;
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}
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@ -170,7 +165,8 @@ int tipc_group_size(struct tipc_group *grp)
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}
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struct tipc_group *tipc_group_create(struct net *net, u32 portid,
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struct tipc_group_req *mreq)
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struct tipc_group_req *mreq,
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bool *group_is_open)
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{
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u32 filter = TIPC_SUB_PORTS | TIPC_SUB_NO_STATUS;
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bool global = mreq->scope != TIPC_NODE_SCOPE;
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@ -192,6 +188,7 @@ struct tipc_group *tipc_group_create(struct net *net, u32 portid,
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grp->scope = mreq->scope;
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grp->loopback = mreq->flags & TIPC_GROUP_LOOPBACK;
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grp->events = mreq->flags & TIPC_GROUP_MEMBER_EVTS;
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grp->open = group_is_open;
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filter |= global ? TIPC_SUB_CLUSTER_SCOPE : TIPC_SUB_NODE_SCOPE;
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if (tipc_topsrv_kern_subscr(net, portid, type, 0, ~0,
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filter, &grp->subid))
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@ -430,7 +427,7 @@ bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
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if (m->window >= len)
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return false;
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grp->open = false;
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*grp->open = false;
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/* If not fully advertised, do it now to prevent mutual blocking */
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adv = m->advertised;
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@ -453,7 +450,7 @@ bool tipc_group_bc_cong(struct tipc_group *grp, int len)
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/* If prev bcast was replicast, reject until all receivers have acked */
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if (grp->bc_ackers) {
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grp->open = false;
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*grp->open = false;
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return true;
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}
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if (list_empty(&grp->small_win))
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@ -800,7 +797,7 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
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if (--grp->bc_ackers)
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return;
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list_del_init(&m->small_win);
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m->group->open = true;
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*m->group->open = true;
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*usr_wakeup = true;
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tipc_group_update_member(m, 0);
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return;
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@ -43,7 +43,8 @@ struct tipc_member;
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struct tipc_msg;
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struct tipc_group *tipc_group_create(struct net *net, u32 portid,
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struct tipc_group_req *mreq);
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struct tipc_group_req *mreq,
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bool *group_is_open);
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void tipc_group_join(struct net *net, struct tipc_group *grp, int *sk_rcv_buf);
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void tipc_group_delete(struct net *net, struct tipc_group *grp);
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void tipc_group_add_member(struct tipc_group *grp, u32 node,
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@ -67,7 +68,6 @@ void tipc_group_update_bc_members(struct tipc_group *grp, int len, bool ack);
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bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
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int len, struct tipc_member **m);
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bool tipc_group_bc_cong(struct tipc_group *grp, int len);
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bool tipc_group_is_open(struct tipc_group *grp);
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void tipc_group_update_rcv_win(struct tipc_group *grp, int blks, u32 node,
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u32 port, struct sk_buff_head *xmitq);
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u16 tipc_group_bc_snd_nxt(struct tipc_group *grp);
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@ -116,6 +116,7 @@ struct tipc_sock {
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struct tipc_mc_method mc_method;
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struct rcu_head rcu;
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struct tipc_group *group;
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bool group_is_open;
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};
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static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
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@ -715,7 +716,6 @@ static unsigned int tipc_poll(struct file *file, struct socket *sock,
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{
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struct sock *sk = sock->sk;
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struct tipc_sock *tsk = tipc_sk(sk);
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struct tipc_group *grp;
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u32 revents = 0;
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sock_poll_wait(file, sk_sleep(sk), wait);
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@ -736,8 +736,7 @@ static unsigned int tipc_poll(struct file *file, struct socket *sock,
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revents |= POLLIN | POLLRDNORM;
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break;
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case TIPC_OPEN:
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grp = tsk->group;
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if ((!grp || tipc_group_is_open(grp)) && !tsk->cong_link_cnt)
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if (tsk->group_is_open && !tsk->cong_link_cnt)
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revents |= POLLOUT;
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if (!tipc_sk_type_connectionless(sk))
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break;
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@ -2758,7 +2757,7 @@ static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
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return -EINVAL;
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if (grp)
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return -EACCES;
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grp = tipc_group_create(net, tsk->portid, mreq);
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grp = tipc_group_create(net, tsk->portid, mreq, &tsk->group_is_open);
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if (!grp)
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return -ENOMEM;
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tsk->group = grp;
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