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authorJon Maloy <jon.maloy@ericsson.com>2018-01-17 16:42:46 +0100
committerDavid S. Miller <davem@davemloft.net>2018-01-19 15:12:21 -0500
commit60c2530696320ee6ffe4491c17079fa403790c98 (patch)
tree619bdaecd86e48c1962a6866e40ada7e09c5addc /net/tipc/socket.c
parent30c3e9d470358a6741e00e1034a1ea85c6a516f0 (diff)
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>
Diffstat (limited to 'net/tipc/socket.c')
-rw-r--r--net/tipc/socket.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index d799e50ff722..473a096b6fba 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;