This is a note to let you know that I've just added the patch titled can: isotp: stop timeout monitoring when no first frame was sent to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: can-isotp-stop-timeout-monitoring-when-no-first-fram.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit e14e256d3f6dbc93babbbf2052eca459315c2970 Author: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Date: Tue Apr 5 19:51:12 2022 +0200 can: isotp: stop timeout monitoring when no first frame was sent [ Upstream commit d73497081710c876c3c61444445512989e102152 ] The first attempt to fix a the 'impossible' WARN_ON_ONCE(1) in isotp_tx_timer_handler() focussed on the identical CAN IDs created by the syzbot reproducer and lead to upstream fix/commit 3ea566422cbd ("can: isotp: sanitize CAN ID checks in isotp_bind()"). But this did not catch the root cause of the wrong tx.state in the tx_timer handler. In the isotp 'first frame' case a timeout monitoring needs to be started before the 'first frame' is send. But when this sending failed the timeout monitoring for this specific frame has to be disabled too. Otherwise the tx_timer is fired with the 'warn me' tx.state of ISOTP_IDLE. Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Link: https://lore.kernel.org/all/20220405175112.2682-1-socketcan@xxxxxxxxxxxx Reported-by: syzbot+2339c27f5c66c652843e@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/can/isotp.c b/net/can/isotp.c index 5bce7c66c121..8c753dcefe7f 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -866,6 +866,7 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) struct canfd_frame *cf; int ae = (so->opt.flags & CAN_ISOTP_EXTEND_ADDR) ? 1 : 0; int wait_tx_done = (so->opt.flags & CAN_ISOTP_WAIT_TX_DONE) ? 1 : 0; + s64 hrtimer_sec = 0; int off; int err; @@ -964,7 +965,9 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) isotp_create_fframe(cf, so, ae); /* start timeout for FC */ - hrtimer_start(&so->txtimer, ktime_set(1, 0), HRTIMER_MODE_REL_SOFT); + hrtimer_sec = 1; + hrtimer_start(&so->txtimer, ktime_set(hrtimer_sec, 0), + HRTIMER_MODE_REL_SOFT); } /* send the first or only CAN frame */ @@ -977,6 +980,11 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) if (err) { pr_notice_once("can-isotp: %s: can_send_ret %pe\n", __func__, ERR_PTR(err)); + + /* no transmission -> no timeout monitoring */ + if (hrtimer_sec) + hrtimer_cancel(&so->txtimer); + goto err_out_drop; }