From: Martin Schiller <ms@dev.tdt.de>
To: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: Andrew Hendry <andrew.hendry@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-x25@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, yuanxzhang@fudan.edu.cn,
kjlu@umn.edu, Xin Tan <tanxin.ctf@gmail.com>
Subject: Re: [PATCH 1/2] net/x25: Fix x25_neigh refcnt leak when x25_connect() fails
Date: Thu, 23 Apr 2020 09:00:42 +0200 [thread overview]
Message-ID: <fccc5247bb916ccbd9a4c2ef8c6e76e4@dev.tdt.de> (raw)
In-Reply-To: <1587618822-13544-1-git-send-email-xiyuyang19@fudan.edu.cn>
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)
prev parent reply other threads:[~2020-04-23 7:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 5:13 [PATCH 1/2] net/x25: Fix x25_neigh refcnt leak when x25_connect() fails Xiyu Yang
2020-04-23 6:36 ` Yuehaibing
2020-04-23 7:00 ` Martin Schiller [this message]
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