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Date: Wed, 17 Jan 2018 16:42:46 +0100
From: Jon Maloy <jon.maloy@...csson.com>
To: <davem@...emloft.net>, <netdev@...r.kernel.org>
CC: <mohan.krishna.ghanta.krishnamurthy@...csson.com>,
<tung.q.nguyen@...tech.com.au>, <hoang.h.le@...tech.com.au>,
<jon.maloy@...csson.com>, <canh.d.luu@...tech.com.au>,
<ying.xue@...driver.com>, <tipc-discussion@...ts.sourceforge.net>
Subject: [net-next 1/1] 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@...kaller.appspotmail.com
Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
---
net/tipc/group.c | 19 ++++++++-----------
net/tipc/group.h | 4 ++--
net/tipc/socket.c | 7 +++----
3 files changed, 13 insertions(+), 17 deletions(-)
diff --git a/net/tipc/group.c b/net/tipc/group.c
index 497ee34..122162a 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -93,26 +93,21 @@ struct tipc_group {
u16 max_active;
u16 bc_snd_nxt;
u16 bc_ackers;
+ bool *open;
bool loopback;
bool events;
- bool open;
};
static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
int mtyp, struct sk_buff_head *xmitq);
-bool tipc_group_is_open(struct tipc_group *grp)
-{
- return grp->open;
-}
-
static void tipc_group_open(struct tipc_member *m, bool *wakeup)
{
*wakeup = false;
if (list_empty(&m->small_win))
return;
list_del_init(&m->small_win);
- m->group->open = true;
+ *m->group->open = true;
*wakeup = true;
}
@@ -170,7 +165,8 @@ int tipc_group_size(struct tipc_group *grp)
}
struct tipc_group *tipc_group_create(struct net *net, u32 portid,
- struct tipc_group_req *mreq)
+ struct tipc_group_req *mreq,
+ bool *group_is_open)
{
u32 filter = TIPC_SUB_PORTS | TIPC_SUB_NO_STATUS;
bool global = mreq->scope != TIPC_NODE_SCOPE;
@@ -192,6 +188,7 @@ struct tipc_group *tipc_group_create(struct net *net, u32 portid,
grp->scope = mreq->scope;
grp->loopback = mreq->flags & TIPC_GROUP_LOOPBACK;
grp->events = mreq->flags & TIPC_GROUP_MEMBER_EVTS;
+ grp->open = group_is_open;
filter |= global ? TIPC_SUB_CLUSTER_SCOPE : TIPC_SUB_NODE_SCOPE;
if (tipc_topsrv_kern_subscr(net, portid, type, 0, ~0,
filter, &grp->subid))
@@ -430,7 +427,7 @@ bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
if (m->window >= len)
return false;
- grp->open = false;
+ *grp->open = false;
/* If not fully advertised, do it now to prevent mutual blocking */
adv = m->advertised;
@@ -453,7 +450,7 @@ bool tipc_group_bc_cong(struct tipc_group *grp, int len)
/* If prev bcast was replicast, reject until all receivers have acked */
if (grp->bc_ackers) {
- grp->open = false;
+ *grp->open = false;
return true;
}
if (list_empty(&grp->small_win))
@@ -800,7 +797,7 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
if (--grp->bc_ackers)
return;
list_del_init(&m->small_win);
- m->group->open = true;
+ *m->group->open = true;
*usr_wakeup = true;
tipc_group_update_member(m, 0);
return;
diff --git a/net/tipc/group.h b/net/tipc/group.h
index f4a596e..5996af6 100644
--- a/net/tipc/group.h
+++ b/net/tipc/group.h
@@ -43,7 +43,8 @@ struct tipc_member;
struct tipc_msg;
struct tipc_group *tipc_group_create(struct net *net, u32 portid,
- struct tipc_group_req *mreq);
+ struct tipc_group_req *mreq,
+ bool *group_is_open);
void tipc_group_join(struct net *net, struct tipc_group *grp, int *sk_rcv_buf);
void tipc_group_delete(struct net *net, struct tipc_group *grp);
void tipc_group_add_member(struct tipc_group *grp, u32 node,
@@ -67,7 +68,6 @@ void tipc_group_update_bc_members(struct tipc_group *grp, int len, bool ack);
bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
int len, struct tipc_member **m);
bool tipc_group_bc_cong(struct tipc_group *grp, int len);
-bool tipc_group_is_open(struct tipc_group *grp);
void tipc_group_update_rcv_win(struct tipc_group *grp, int blks, u32 node,
u32 port, struct sk_buff_head *xmitq);
u16 tipc_group_bc_snd_nxt(struct tipc_group *grp);
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 18fca5b..5d9a590 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -116,6 +116,7 @@ struct tipc_sock {
struct tipc_mc_method mc_method;
struct rcu_head rcu;
struct tipc_group *group;
+ bool group_is_open;
};
static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
@@ -715,7 +716,6 @@ static unsigned int tipc_poll(struct file *file, struct socket *sock,
{
struct sock *sk = sock->sk;
struct tipc_sock *tsk = tipc_sk(sk);
- struct tipc_group *grp;
u32 revents = 0;
sock_poll_wait(file, sk_sleep(sk), wait);
@@ -736,8 +736,7 @@ static unsigned int tipc_poll(struct file *file, struct socket *sock,
revents |= POLLIN | POLLRDNORM;
break;
case TIPC_OPEN:
- grp = tsk->group;
- if ((!grp || tipc_group_is_open(grp)) && !tsk->cong_link_cnt)
+ if (tsk->group_is_open && !tsk->cong_link_cnt)
revents |= POLLOUT;
if (!tipc_sk_type_connectionless(sk))
break;
@@ -2758,7 +2757,7 @@ static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
return -EINVAL;
if (grp)
return -EACCES;
- grp = tipc_group_create(net, tsk->portid, mreq);
+ grp = tipc_group_create(net, tsk->portid, mreq, &tsk->group_is_open);
if (!grp)
return -ENOMEM;
tsk->group = grp;
--
2.1.4
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