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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>
This commit is contained in:
Jon Maloy 2018-01-17 16:42:46 +01:00 committed by David S. Miller
parent 30c3e9d470
commit 60c2530696
3 changed files with 13 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
net/tipc/group.c
View File

@ -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;

4
net/tipc/group.h
View File

@ -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);

7
net/tipc/socket.c
View File

@ -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;