* [PATCH v2] net/x25: Fix x25_neigh refcnt leak when x25 disconnect
@ 2020-04-25 13:06 Xiyu Yang
2020-04-27 18:20 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Xiyu Yang @ 2020-04-25 13:06 UTC (permalink / raw)
To: Andrew Hendry, David S. Miller, Jakub Kicinski, Xiyu Yang,
Xin Tan, Greg Kroah-Hartman, Allison Randal, Thomas Gleixner,
linux-x25, netdev, linux-kernel
Cc: yuanxzhang, kjlu
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 success and returns, the reference still be hold by
"x25->neighbour", so the refcount should be decreased in
x25_disconnect() to keep refcount balanced.
The reference counting issue happens in x25_disconnect(), which forgets
to decrease the refcnt increased by x25_get_neigh() in x25_connect(),
causing a refcnt leak.
Fix this issue by calling x25_neigh_put() before x25_disconnect()
returns.
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
Changes in v2:
- Fix x25_neigh refcnt leak in x25_disconnect() rather than in
x25_connect()
---
net/x25/x25_subr.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c
index 8aa415a38814..8b1b06cabcbf 100644
--- a/net/x25/x25_subr.c
+++ b/net/x25/x25_subr.c
@@ -357,6 +357,10 @@ void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
sk->sk_state_change(sk);
sock_set_flag(sk, SOCK_DEAD);
}
+ read_lock_bh(&x25_list_lock);
+ x25_neigh_put(x25->neighbour);
+ x25->neighbour = NULL;
+ read_unlock_bh(&x25_list_lock);
}
/*
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] net/x25: Fix x25_neigh refcnt leak when x25 disconnect
2020-04-25 13:06 [PATCH v2] net/x25: Fix x25_neigh refcnt leak when x25 disconnect Xiyu Yang
@ 2020-04-27 18:20 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2020-04-27 18:20 UTC (permalink / raw)
To: xiyuyang19
Cc: andrew.hendry, kuba, tanxin.ctf, gregkh, allison, tglx,
linux-x25, netdev, linux-kernel, yuanxzhang, kjlu
From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Date: Sat, 25 Apr 2020 21:06:25 +0800
> 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 success and returns, the reference still be hold by
> "x25->neighbour", so the refcount should be decreased in
> x25_disconnect() to keep refcount balanced.
>
> The reference counting issue happens in x25_disconnect(), which forgets
> to decrease the refcnt increased by x25_get_neigh() in x25_connect(),
> causing a refcnt leak.
>
> Fix this issue by calling x25_neigh_put() before x25_disconnect()
> returns.
>
> Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Applied.
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