From: Oliver Hartkopp socketcan@hartkopp.net

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: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Cc: linux-stable stable@vger.kernel.org Signed-off-by: Oliver Hartkopp socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/isotp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c index be6183f8ca11..234cc4ad179a 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -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;