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authorZiyang Xuan <william.xuanziyang@huawei.com>2021-09-06 12:42:00 +0300
committerMarc Kleine-Budde <mkl@pengutronix.de>2023-02-02 12:33:26 +0300
commitd0553680f94c49bbe0e39eb50d033ba563b4212d (patch)
treebdeef8126a819e8fba8ce624fda2a329b796578c /net/can
parent917d5e04d4dd2bbbf36fc6976ba442e284ccc42d (diff)
downloadlinux-d0553680f94c49bbe0e39eb50d033ba563b4212d.tar.xz
can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
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> Acked-by: Oleksij Rempel <o.rempel@pengutronix.de> Link: https://lore.kernel.org/all/20210906094200.95868-1-william.xuanziyang@huawei.com Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'net/can')
-rw-r--r--net/can/j1939/transport.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 5c722b55fe23..fce9b9ebf13f 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1092,10 +1092,6 @@ 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);