* [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
@ 2021-09-06 9:42 Ziyang Xuan
2021-09-08 3:46 ` Oleksij Rempel
2021-09-10 12:40 ` Oleksij Rempel
0 siblings, 2 replies; 5+ messages in thread
From: Ziyang Xuan @ 2021-09-06 9:42 UTC (permalink / raw)
To: robin; +Cc: linux, socketcan, mkl, davem, kuba, linux-can, netdev, linux-kernel
The conclusion "j1939_session_deactivate() should be called with a
session ref-count of at least 2" is incorrect. In some concurrent
scenarios, j1939_session_deactivate can be called with the session
ref-count less than 2. But there is not any problem because it
will check the session active state before session putting in
j1939_session_deactivate_locked().
Here is the concurrent scenario of the problem reported by syzbot
and my reproduction log.
cpu0 cpu1
j1939_xtp_rx_eoma
j1939_xtp_rx_abort_one
j1939_session_get_by_addr [kref == 2]
j1939_session_get_by_addr [kref == 3]
j1939_session_deactivate [kref == 2]
j1939_session_put [kref == 1]
j1939_session_completed
j1939_session_deactivate
WARN_ON_ONCE(kref < 2)
=====================================================
WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70
CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
RIP: 0010:j1939_session_deactivate+0x5f/0x70
Call Trace:
j1939_session_deactivate_activate_next+0x11/0x28
j1939_xtp_rx_eoma+0x12a/0x180
j1939_tp_recv+0x4a2/0x510
j1939_can_recv+0x226/0x380
can_rcv_filter+0xf8/0x220
can_receive+0x102/0x220
? process_backlog+0xf0/0x2c0
can_rcv+0x53/0xf0
__netif_receive_skb_one_core+0x67/0x90
? process_backlog+0x97/0x2c0
__netif_receive_skb+0x22/0x80
Fixes: 0c71437dd50d ("can: j1939: j1939_session_deactivate(): clarify lifetime of session object")
Reported-by: syzbot+9981a614060dcee6eeca@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
net/can/j1939/transport.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index bdc95bd7a851..0f8309314075 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1079,10 +1079,6 @@ static bool j1939_session_deactivate(struct j1939_session *session)
bool active;
j1939_session_list_lock(priv);
- /* This function should be called with a session ref-count of at
- * least 2.
- */
- WARN_ON_ONCE(kref_read(&session->kref) < 2);
active = j1939_session_deactivate_locked(session);
j1939_session_list_unlock(priv);
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
2021-09-06 9:42 [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate Ziyang Xuan
@ 2021-09-08 3:46 ` Oleksij Rempel
2021-09-10 12:40 ` Oleksij Rempel
1 sibling, 0 replies; 5+ messages in thread
From: Oleksij Rempel @ 2021-09-08 3:46 UTC (permalink / raw)
To: Ziyang Xuan
Cc: robin, linux, socketcan, mkl, davem, kuba, linux-can, netdev,
linux-kernel
Hi,
Thank you for your patches. Please stay on hold, I'll review it end of
this week.
On Mon, Sep 06, 2021 at 05:42:00PM +0800, Ziyang Xuan wrote:
> The conclusion "j1939_session_deactivate() should be called with a
> session ref-count of at least 2" is incorrect. In some concurrent
> scenarios, j1939_session_deactivate can be called with the session
> ref-count less than 2. But there is not any problem because it
> will check the session active state before session putting in
> j1939_session_deactivate_locked().
>
> Here is the concurrent scenario of the problem reported by syzbot
> and my reproduction log.
>
> cpu0 cpu1
> j1939_xtp_rx_eoma
> j1939_xtp_rx_abort_one
> j1939_session_get_by_addr [kref == 2]
> j1939_session_get_by_addr [kref == 3]
> j1939_session_deactivate [kref == 2]
> j1939_session_put [kref == 1]
> j1939_session_completed
> j1939_session_deactivate
> WARN_ON_ONCE(kref < 2)
>
> =====================================================
> WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70
> CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
> RIP: 0010:j1939_session_deactivate+0x5f/0x70
> Call Trace:
> j1939_session_deactivate_activate_next+0x11/0x28
> j1939_xtp_rx_eoma+0x12a/0x180
> j1939_tp_recv+0x4a2/0x510
> j1939_can_recv+0x226/0x380
> can_rcv_filter+0xf8/0x220
> can_receive+0x102/0x220
> ? process_backlog+0xf0/0x2c0
> can_rcv+0x53/0xf0
> __netif_receive_skb_one_core+0x67/0x90
> ? process_backlog+0x97/0x2c0
> __netif_receive_skb+0x22/0x80
>
> Fixes: 0c71437dd50d ("can: j1939: j1939_session_deactivate(): clarify lifetime of session object")
> Reported-by: syzbot+9981a614060dcee6eeca@syzkaller.appspotmail.com
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
> net/can/j1939/transport.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index bdc95bd7a851..0f8309314075 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -1079,10 +1079,6 @@ static bool j1939_session_deactivate(struct j1939_session *session)
> bool active;
>
> j1939_session_list_lock(priv);
> - /* This function should be called with a session ref-count of at
> - * least 2.
> - */
> - WARN_ON_ONCE(kref_read(&session->kref) < 2);
> active = j1939_session_deactivate_locked(session);
> j1939_session_list_unlock(priv);
>
> --
> 2.25.1
>
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
2021-09-06 9:42 [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate Ziyang Xuan
2021-09-08 3:46 ` Oleksij Rempel
@ 2021-09-10 12:40 ` Oleksij Rempel
2021-11-10 2:00 ` Ziyang Xuan (William)
2023-01-14 17:35 ` Fedor Pchelkin
1 sibling, 2 replies; 5+ messages in thread
From: Oleksij Rempel @ 2021-09-10 12:40 UTC (permalink / raw)
To: Ziyang Xuan
Cc: robin, linux, socketcan, mkl, davem, kuba, linux-can, netdev,
linux-kernel
On Mon, Sep 06, 2021 at 05:42:00PM +0800, Ziyang Xuan wrote:
> The conclusion "j1939_session_deactivate() should be called with a
> session ref-count of at least 2" is incorrect. In some concurrent
> scenarios, j1939_session_deactivate can be called with the session
> ref-count less than 2. But there is not any problem because it
> will check the session active state before session putting in
> j1939_session_deactivate_locked().
>
> Here is the concurrent scenario of the problem reported by syzbot
> and my reproduction log.
>
> cpu0 cpu1
> j1939_xtp_rx_eoma
> j1939_xtp_rx_abort_one
> j1939_session_get_by_addr [kref == 2]
> j1939_session_get_by_addr [kref == 3]
> j1939_session_deactivate [kref == 2]
> j1939_session_put [kref == 1]
> j1939_session_completed
> j1939_session_deactivate
> WARN_ON_ONCE(kref < 2)
>
Ok, I see, this warning makes sense only if session will actually be
deactivated.
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Thank you!
> =====================================================
> WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70
> CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
> RIP: 0010:j1939_session_deactivate+0x5f/0x70
> Call Trace:
> j1939_session_deactivate_activate_next+0x11/0x28
> j1939_xtp_rx_eoma+0x12a/0x180
> j1939_tp_recv+0x4a2/0x510
> j1939_can_recv+0x226/0x380
> can_rcv_filter+0xf8/0x220
> can_receive+0x102/0x220
> ? process_backlog+0xf0/0x2c0
> can_rcv+0x53/0xf0
> __netif_receive_skb_one_core+0x67/0x90
> ? process_backlog+0x97/0x2c0
> __netif_receive_skb+0x22/0x80
>
> Fixes: 0c71437dd50d ("can: j1939: j1939_session_deactivate(): clarify lifetime of session object")
> Reported-by: syzbot+9981a614060dcee6eeca@syzkaller.appspotmail.com
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
> net/can/j1939/transport.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index bdc95bd7a851..0f8309314075 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -1079,10 +1079,6 @@ static bool j1939_session_deactivate(struct j1939_session *session)
> bool active;
>
> j1939_session_list_lock(priv);
> - /* This function should be called with a session ref-count of at
> - * least 2.
> - */
> - WARN_ON_ONCE(kref_read(&session->kref) < 2);
> active = j1939_session_deactivate_locked(session);
> j1939_session_list_unlock(priv);
>
> --
> 2.25.1
>
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
2021-09-10 12:40 ` Oleksij Rempel
@ 2021-11-10 2:00 ` Ziyang Xuan (William)
2023-01-14 17:35 ` Fedor Pchelkin
1 sibling, 0 replies; 5+ messages in thread
From: Ziyang Xuan (William) @ 2021-11-10 2:00 UTC (permalink / raw)
To: Oleksij Rempel, Marc Kleine-Budde
Cc: robin, linux, socketcan, mkl, davem, kuba, linux-can, netdev,
linux-kernel
Hello,
I notice that the patch is not applied in upstream. Is it missed
or any other problems?
Thank you!
> On Mon, Sep 06, 2021 at 05:42:00PM +0800, Ziyang Xuan wrote:
>> The conclusion "j1939_session_deactivate() should be called with a
>> session ref-count of at least 2" is incorrect. In some concurrent
>> scenarios, j1939_session_deactivate can be called with the session
>> ref-count less than 2. But there is not any problem because it
>> will check the session active state before session putting in
>> j1939_session_deactivate_locked().
>>
>> Here is the concurrent scenario of the problem reported by syzbot
>> and my reproduction log.
>>
>> cpu0 cpu1
>> j1939_xtp_rx_eoma
>> j1939_xtp_rx_abort_one
>> j1939_session_get_by_addr [kref == 2]
>> j1939_session_get_by_addr [kref == 3]
>> j1939_session_deactivate [kref == 2]
>> j1939_session_put [kref == 1]
>> j1939_session_completed
>> j1939_session_deactivate
>> WARN_ON_ONCE(kref < 2)
>>
>
> Ok, I see, this warning makes sense only if session will actually be
> deactivated.
>
> Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
>
> Thank you!
>
>> =====================================================
>> WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70
>> CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
>> RIP: 0010:j1939_session_deactivate+0x5f/0x70
>> Call Trace:
>> j1939_session_deactivate_activate_next+0x11/0x28
>> j1939_xtp_rx_eoma+0x12a/0x180
>> j1939_tp_recv+0x4a2/0x510
>> j1939_can_recv+0x226/0x380
>> can_rcv_filter+0xf8/0x220
>> can_receive+0x102/0x220
>> ? process_backlog+0xf0/0x2c0
>> can_rcv+0x53/0xf0
>> __netif_receive_skb_one_core+0x67/0x90
>> ? process_backlog+0x97/0x2c0
>> __netif_receive_skb+0x22/0x80
>>
>> Fixes: 0c71437dd50d ("can: j1939: j1939_session_deactivate(): clarify lifetime of session object")
>> Reported-by: syzbot+9981a614060dcee6eeca@syzkaller.appspotmail.com
>> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
>> ---
>> net/can/j1939/transport.c | 4 ----
>> 1 file changed, 4 deletions(-)
>>
>> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
>> index bdc95bd7a851..0f8309314075 100644
>> --- a/net/can/j1939/transport.c
>> +++ b/net/can/j1939/transport.c
>> @@ -1079,10 +1079,6 @@ static bool j1939_session_deactivate(struct j1939_session *session)
>> bool active;
>>
>> j1939_session_list_lock(priv);
>> - /* This function should be called with a session ref-count of at
>> - * least 2.
>> - */
>> - WARN_ON_ONCE(kref_read(&session->kref) < 2);
>> active = j1939_session_deactivate_locked(session);
>> j1939_session_list_unlock(priv);
>>
>> --
>> 2.25.1
>>
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
2021-09-10 12:40 ` Oleksij Rempel
2021-11-10 2:00 ` Ziyang Xuan (William)
@ 2023-01-14 17:35 ` Fedor Pchelkin
1 sibling, 0 replies; 5+ messages in thread
From: Fedor Pchelkin @ 2023-01-14 17:35 UTC (permalink / raw)
To: Oleksij Rempel
Cc: Fedor Pchelkin, Ziyang Xuan, robin, linux, Oliver Hartkopp,
Marc Kleine-Budde, David S. Miller, Jakub Kicinski, linux-can,
netdev, linux-kernel, Alexey Khoroshilov, lvc-project
Hello,
On Fri, 10 Sep 2021 14:40:05 +0200, Oleksij Rempel wrote:
> Ok, I see, this warning makes sense only if session will actually be
> deactivated.
>
> Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
>
> Thank you!
As Ziyang Xuan stated, the patch was not applied to upstream.
Usage of WARN_ON_ONCE in this case is actually discouraged: it erroneusly
complains in a valid situation.
So the macro should be removed with the aforementioned patch. If it makes
some sense for debugging purposes, WARN_ON_ONCE can be replaced with
netdev_warn/netdev_notice but anyway discard of WARN_ON_ONCE.
--
Regards,
Fedor
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-01-14 17:36 UTC | newest]
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2021-09-06 9:42 [PATCH net] can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate Ziyang Xuan
2021-09-08 3:46 ` Oleksij Rempel
2021-09-10 12:40 ` Oleksij Rempel
2021-11-10 2:00 ` Ziyang Xuan (William)
2023-01-14 17:35 ` Fedor Pchelkin
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