| Message ID | 1587618822-13544-1-git-send-email-xiyuyang19@fudan.edu.cn |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | [1/2] net/x25: Fix x25_neigh refcnt leak when x25_connect() fails | expand |
On 2020/4/23 13:13, Xiyu Yang wrote: > x25_connect() invokes x25_get_neigh(), which returns a reference of the > specified x25_neigh object to "x25->neighbour" with increased refcnt. > > When x25_connect() returns, local variable "x25" and "x25->neighbour" > become invalid, so the refcount should be decreased to keep refcount > balanced. > > The reference counting issue happens in one exception handling path of > x25_connect(). When sock state is not TCP_ESTABLISHED and its flags > include O_NONBLOCK, the function forgets to decrease the refcnt > increased by x25_get_neigh(), causing a refcnt leak. > > Fix this issue by jumping to "out_put_neigh" label when x25_connect() > fails. > > Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> > Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> > --- > net/x25/af_x25.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c > index d5b09bbff375..e6571c56209b 100644 > --- a/net/x25/af_x25.c > +++ b/net/x25/af_x25.c > @@ -816,7 +816,7 @@ static int x25_connect(struct socket *sock, struct sockaddr *uaddr, > /* Now the loop */ > rc = -EINPROGRESS; > if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) > - goto out; > + goto out_put_neigh; This seems not right, see commit e21dba7a4df4 ("net/x25: fix nonblocking connect") > > rc = x25_wait_for_connection_establishment(sk); > if (rc) >
On 2020-04-23 07:13, Xiyu Yang wrote: > x25_connect() invokes x25_get_neigh(), which returns a reference of the > specified x25_neigh object to "x25->neighbour" with increased refcnt. > > When x25_connect() returns, local variable "x25" and "x25->neighbour" > become invalid, so the refcount should be decreased to keep refcount > balanced. > > The reference counting issue happens in one exception handling path of > x25_connect(). When sock state is not TCP_ESTABLISHED and its flags > include O_NONBLOCK, the function forgets to decrease the refcnt > increased by x25_get_neigh(), causing a refcnt leak. > > Fix this issue by jumping to "out_put_neigh" label when x25_connect() > fails. I don't agree with that. Please have a look at commit e21dba7a4df4 ("net/x25: fix nonblocking connect). But I also think you are right and there seems to be a refcnt leak, which should be fixed by a call to x25_neigh_put() in the x25_disconnect() function. - Martin > > Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> > Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> > --- > net/x25/af_x25.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c > index d5b09bbff375..e6571c56209b 100644 > --- a/net/x25/af_x25.c > +++ b/net/x25/af_x25.c > @@ -816,7 +816,7 @@ static int x25_connect(struct socket *sock, struct > sockaddr *uaddr, > /* Now the loop */ > rc = -EINPROGRESS; > if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) > - goto out; > + goto out_put_neigh; > > rc = x25_wait_for_connection_establishment(sk); > if (rc)
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index d5b09bbff375..e6571c56209b 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -816,7 +816,7 @@ static int x25_connect(struct socket *sock, struct sockaddr *uaddr, /* Now the loop */ rc = -EINPROGRESS; if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) - goto out; + goto out_put_neigh; rc = x25_wait_for_connection_establishment(sk); if (rc)