diff options
| author | Xie He <xie.he.0141@gmail.com> | 2020-12-27 18:53:39 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-12 20:18:13 +0100 |
| commit | 8ca1d23e6ad31e6df425221eaf82605137a9d803 (patch) | |
| tree | 567a556ee8e343dc3f065b9445273e2d46284bf8 /drivers/net/wan | |
| parent | 0d6eeee3b9d4e08a9698038998d2752f157207f3 (diff) | |
net: hdlc_ppp: Fix issues when mod_timer is called while timer is running
[ Upstream commit 1fef73597fa545c35fddc953979013882fbd4e55 ]
ppp_cp_event is called directly or indirectly by ppp_rx with "ppp->lock"
held. It may call mod_timer to add a new timer. However, at the same time
ppp_timer may be already running and waiting for "ppp->lock". In this
case, there's no need for ppp_timer to continue running and it can just
exit.
If we let ppp_timer continue running, it may call add_timer. This causes
kernel panic because add_timer can't be called with a timer pending.
This patch fixes this problem.
Fixes: e022c2f07ae5 ("WAN: new synchronous PPP implementation for generic HDLC.")
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net/wan')
| -rw-r--r-- | drivers/net/wan/hdlc_ppp.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c index 64f855651336..261b53fc8e04 100644 --- a/drivers/net/wan/hdlc_ppp.c +++ b/drivers/net/wan/hdlc_ppp.c @@ -569,6 +569,13 @@ static void ppp_timer(struct timer_list *t) unsigned long flags; spin_lock_irqsave(&ppp->lock, flags); + /* mod_timer could be called after we entered this function but + * before we got the lock. + */ + if (timer_pending(&proto->timer)) { + spin_unlock_irqrestore(&ppp->lock, flags); + return; + } switch (proto->state) { case STOPPING: case REQ_SENT: |