Commit 14a4696b authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
Browse files

can: isotp: isotp_release(): omit unintended hrtimer restart on socket release 

When closing the isotp socket, the potentially running hrtimers are
canceled before removing the subscription for CAN identifiers via
can_rx_unregister().

This may lead to an unintended (re)start of a hrtimer in
isotp_rcv_cf() and isotp_rcv_fc() in the case that a CAN frame is
received by isotp_rcv() while the subscription removal is processed.

However, isotp_rcv() is called under RCU protection, so after calling
can_rx_unregister, we may call synchronize_rcu in order to wait for
any RCU read-side critical sections to finish. This prevents the
reception of CAN frames after hrtimer_cancel() and therefore the
unintended (re)start of the hrtimers.

Link: https://lore.kernel.org/r/20210618173713.2296-1-socketcan@hartkopp.net


Fixes: e057dd3f ("can: add ISO 15765-2:2016 transport protocol")
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent fb8696ab

net/can/isotp.c

+4 −3
Original line number Diff line number Diff line
@@ -1028,9 +1028,6 @@ static int isotp_release(struct socket *sock) 


	lock_sock(sk);



	hrtimer_cancel(&so->txtimer);

	hrtimer_cancel(&so->rxtimer);



	/* remove current filters & unregister */

	if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) {

		if (so->ifindex) {
@@ -1042,10 +1039,14 @@ static int isotp_release(struct socket *sock) 
						  SINGLE_MASK(so->rxid),

						  isotp_rcv, sk);

				dev_put(dev);

				synchronize_rcu();

			}

		}

	}



	hrtimer_cancel(&so->txtimer);

	hrtimer_cancel(&so->rxtimer);



	so->ifindex = 0;

	so->bound = 0;