This is a note to let you know that I've just added the patch titled
can: isotp: fix race between isotp_sendsmg() and isotp_release()
to the 6.2-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-fix-race-between-isotp_sendsmg-and-isotp_release.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 051737439eaee5bdd03d3c2ef5510d54a478fd05 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Date: Fri, 31 Mar 2023 15:19:35 +0200
Subject: can: isotp: fix race between isotp_sendsmg() and isotp_release()
From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
commit 051737439eaee5bdd03d3c2ef5510d54a478fd05 upstream.
As discussed with Dae R. Jeong and Hillf Danton here [1] the sendmsg()
function in isotp.c might get into a race condition when restoring the
former tx.state from the old_state.
Remove the old_state concept and implement proper locking for the
ISOTP_IDLE transitions in isotp_sendmsg(), inspired by a
simplification idea from Hillf Danton.
Introduce a new tx.state ISOTP_SHUTDOWN and use the same locking
mechanism from isotp_release() which resolves a potential race between
isotp_sendsmg() and isotp_release().
[1] https://lore.kernel.org/linux-can/ZB%2F93xJxq%2FBUqAgG@dragonet
v1: https://lore.kernel.org/all/20230331102114.15164-1-socketcan@xxxxxxxxxxxx
v2: https://lore.kernel.org/all/20230331123600.3550-1-socketcan@xxxxxxxxxxxx
take care of signal interrupts for wait_event_interruptible() in
isotp_release()
v3: https://lore.kernel.org/all/20230331130654.9886-1-socketcan@xxxxxxxxxxxx
take care of signal interrupts for wait_event_interruptible() in
isotp_sendmsg() in the wait_tx_done case
v4: https://lore.kernel.org/all/20230331131935.21465-1-socketcan@xxxxxxxxxxxx
take care of signal interrupts for wait_event_interruptible() in
isotp_sendmsg() in ALL cases
Cc: Dae R. Jeong <threeearcat@xxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Fixes: 4f027cba8216 ("can: isotp: split tx timer into transmission and timeout")
Link: https://lore.kernel.org/all/20230331131935.21465-1-socketcan@xxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
[mkl: rephrase commit message]
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/can/isotp.c | 55 +++++++++++++++++++++++++++++++------------------------
1 file changed, 31 insertions(+), 24 deletions(-)
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -119,7 +119,8 @@ enum {
ISOTP_WAIT_FIRST_FC,
ISOTP_WAIT_FC,
ISOTP_WAIT_DATA,
- ISOTP_SENDING
+ ISOTP_SENDING,
+ ISOTP_SHUTDOWN,
};
struct tpcon {
@@ -880,8 +881,8 @@ static enum hrtimer_restart isotp_tx_tim
txtimer);
struct sock *sk = &so->sk;
- /* don't handle timeouts in IDLE state */
- if (so->tx.state == ISOTP_IDLE)
+ /* don't handle timeouts in IDLE or SHUTDOWN state */
+ if (so->tx.state == ISOTP_IDLE || so->tx.state == ISOTP_SHUTDOWN)
return HRTIMER_NORESTART;
/* we did not get any flow control or echo frame in time */
@@ -918,7 +919,6 @@ static int isotp_sendmsg(struct socket *
{
struct sock *sk = sock->sk;
struct isotp_sock *so = isotp_sk(sk);
- u32 old_state = so->tx.state;
struct sk_buff *skb;
struct net_device *dev;
struct canfd_frame *cf;
@@ -928,23 +928,24 @@ static int isotp_sendmsg(struct socket *
int off;
int err;
- if (!so->bound)
+ if (!so->bound || so->tx.state == ISOTP_SHUTDOWN)
return -EADDRNOTAVAIL;
+wait_free_buffer:
/* we do not support multiple buffers - for now */
- if (cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SENDING) != ISOTP_IDLE ||
- wq_has_sleeper(&so->wait)) {
- if (msg->msg_flags & MSG_DONTWAIT) {
- err = -EAGAIN;
- goto err_out;
- }
+ if (wq_has_sleeper(&so->wait) && (msg->msg_flags & MSG_DONTWAIT))
+ return -EAGAIN;
- /* wait for complete transmission of current pdu */
- err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
- if (err)
- goto err_out;
+ /* wait for complete transmission of current pdu */
+ err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
+ if (err)
+ goto err_event_drop;
+
+ if (cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SENDING) != ISOTP_IDLE) {
+ if (so->tx.state == ISOTP_SHUTDOWN)
+ return -EADDRNOTAVAIL;
- so->tx.state = ISOTP_SENDING;
+ goto wait_free_buffer;
}
if (!size || size > MAX_MSG_LENGTH) {
@@ -1074,7 +1075,9 @@ static int isotp_sendmsg(struct socket *
if (wait_tx_done) {
/* wait for complete transmission of current pdu */
- wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
+ err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
+ if (err)
+ goto err_event_drop;
if (sk->sk_err)
return -sk->sk_err;
@@ -1082,13 +1085,15 @@ static int isotp_sendmsg(struct socket *
return size;
+err_event_drop:
+ /* got signal: force tx state machine to be idle */
+ so->tx.state = ISOTP_IDLE;
+ hrtimer_cancel(&so->txfrtimer);
+ hrtimer_cancel(&so->txtimer);
err_out_drop:
/* drop this PDU and unlock a potential wait queue */
- old_state = ISOTP_IDLE;
-err_out:
- so->tx.state = old_state;
- if (so->tx.state == ISOTP_IDLE)
- wake_up_interruptible(&so->wait);
+ so->tx.state = ISOTP_IDLE;
+ wake_up_interruptible(&so->wait);
return err;
}
@@ -1150,10 +1155,12 @@ static int isotp_release(struct socket *
net = sock_net(sk);
/* wait for complete transmission of current pdu */
- wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
+ while (wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE) == 0 &&
+ cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SHUTDOWN) != ISOTP_IDLE)
+ ;
/* force state machines to be idle also when a signal occurred */
- so->tx.state = ISOTP_IDLE;
+ so->tx.state = ISOTP_SHUTDOWN;
so->rx.state = ISOTP_IDLE;
spin_lock(&isotp_notifier_lock);
Patches currently in stable-queue which might be from socketcan@xxxxxxxxxxxx are
queue-6.2/can-isotp-isotp_recvmsg-use-sock_recv_cmsgs-to-get-sock_rxq_ovfl-infos.patch
queue-6.2/can-isotp-isotp_ops-fix-poll-to-not-report-false-epollout-events.patch
queue-6.2/can-isotp-fix-race-between-isotp_sendsmg-and-isotp_release.patch
