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 <[email protected]>
> Signed-off-by: Xin Tan <[email protected]>
> ---
> 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)