Re: [PATCH 1/2] net/x25: Fix x25_neigh refcnt leak when x25_connect() fails
From: Yuehaibing
Date: Thu Apr 23 2020 - 02:37:00 EST
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@xxxxxxxxxxxx>
> Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
> ---
> 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)
>