[PATCH net 1/4] can: af_can: fix NULL pointer dereference in can_rcv_filter

[PATCH net 1/4] can: af_can: fix NULL pointer dereference in can_rcv_filter

[Marc Kleine-Budde]

From: Oliver Hartkopp <socketcan@hartkopp.net>

Analogue to commit 8aa59e355949 ("can: af_can: fix NULL pointer
dereference in can_rx_register()") we need to check for a missing
initialization of ml_priv in the receive path of CAN frames.

Since commit 4e096a18867a ("net: introduce CAN specific pointer in the
struct net_device") the check for dev->type to be ARPHRD_CAN is not
sufficient anymore since bonding or tun netdevices claim to be CAN
devices but do not initialize ml_priv accordingly.

Fixes: 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device")
Reported-by: syzbot+2d7f58292cb5b29eb5ad@syzkaller.appspotmail.com
Reported-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20221206201259.3028-1-socketcan@hartkopp.net
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/af_can.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 27dcdcc0b808..c69168f11e44 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -677,7 +677,7 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 		   struct packet_type *pt, struct net_device *orig_dev)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_can_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_can_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
@@ -692,7 +692,7 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 		     struct packet_type *pt, struct net_device *orig_dev)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_canfd_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
@@ -707,7 +707,7 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
 		     struct packet_type *pt, struct net_device *orig_dev)
 {
-	if (unlikely(dev->type != ARPHRD_CAN || (!can_is_canxl_skb(skb)))) {
+	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canxl_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 

base-commit: 1799c1b85e292fbfad99892bbea0beee925149e8
-- 
2.35.1

Re: [PATCH net 1/4] can: af_can: fix NULL pointer dereference in can_rcv_filter

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Marc Kleine-Budde <mkl@pengutronix.de>:

On Wed,  7 Dec 2022 11:52:40 +0100 you wrote:
> From: Oliver Hartkopp <socketcan@hartkopp.net>
> 
> Analogue to commit 8aa59e355949 ("can: af_can: fix NULL pointer
> dereference in can_rx_register()") we need to check for a missing
> initialization of ml_priv in the receive path of CAN frames.
> 
> Since commit 4e096a18867a ("net: introduce CAN specific pointer in the
> struct net_device") the check for dev->type to be ARPHRD_CAN is not
> sufficient anymore since bonding or tun netdevices claim to be CAN
> devices but do not initialize ml_priv accordingly.
> 
> [...]

Here is the summary with links:
  - [net,1/4] can: af_can: fix NULL pointer dereference in can_rcv_filter
    https://git.kernel.org/netdev/net/c/0acc442309a0
  - [net,2/4] can: slcan: fix freed work crash
    https://git.kernel.org/netdev/net/c/fb855e9f3b6b
  - [net,3/4] can: can327: flush TX_work on ldisc .close()
    https://git.kernel.org/netdev/net/c/f4a4d121ebec
  - [net,4/4] can: esd_usb: Allow REC and TEC to return to zero
    https://git.kernel.org/netdev/net/c/918ee4911f7a

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net 2/4] can: slcan: fix freed work crash

[Marc Kleine-Budde]

From: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>

The LTP test pty03 is causing a crash in slcan:
  BUG: kernel NULL pointer dereference, address: 0000000000000008
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 0 PID: 348 Comm: kworker/0:3 Not tainted 6.0.8-1-default #1 openSUSE Tumbleweed 9d20364b934f5aab0a9bdf84e8f45cfdfae39dab
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014
  Workqueue:  0x0 (events)
  RIP: 0010:process_one_work (/home/rich/kernel/linux/kernel/workqueue.c:706 /home/rich/kernel/linux/kernel/workqueue.c:2185)
  Code: 49 89 ff 41 56 41 55 41 54 55 53 48 89 f3 48 83 ec 10 48 8b 06 48 8b 6f 48 49 89 c4 45 30 e4 a8 04 b8 00 00 00 00 4c 0f 44 e0 <49> 8b 44 24 08 44 8b a8 00 01 00 00 41 83 e5 20 f6 45 10 04 75 0e
  RSP: 0018:ffffaf7b40f47e98 EFLAGS: 00010046
  RAX: 0000000000000000 RBX: ffff9d644e1b8b48 RCX: ffff9d649e439968
  RDX: 00000000ffff8455 RSI: ffff9d644e1b8b48 RDI: ffff9d64764aa6c0
  RBP: ffff9d649e4335c0 R08: 0000000000000c00 R09: ffff9d64764aa734
  R10: 0000000000000007 R11: 0000000000000001 R12: 0000000000000000
  R13: ffff9d649e4335e8 R14: ffff9d64490da780 R15: ffff9d64764aa6c0
  FS:  0000000000000000(0000) GS:ffff9d649e400000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000008 CR3: 0000000036424000 CR4: 00000000000006f0
  Call Trace:
   <TASK>
  worker_thread (/home/rich/kernel/linux/kernel/workqueue.c:2436)
  kthread (/home/rich/kernel/linux/kernel/kthread.c:376)
  ret_from_fork (/home/rich/kernel/linux/arch/x86/entry/entry_64.S:312)

Apparently, the slcan's tx_work is freed while being scheduled. While
slcan_netdev_close() (netdev side) calls flush_work(&sl->tx_work),
slcan_close() (tty side) does not. So when the netdev is never set UP,
but the tty is stuffed with bytes and forced to wakeup write, the work
is scheduled, but never flushed.

So add an additional flush_work() to slcan_close() to be sure the work
is flushed under all circumstances.

The Fixes commit below moved flush_work() from slcan_close() to
slcan_netdev_close(). What was the rationale behind it? Maybe we can
drop the one in slcan_netdev_close()?

I see the same pattern in can327. So it perhaps needs the very same fix.

Fixes: cfcb4465e992 ("can: slcan: remove legacy infrastructure")
Link: https://bugzilla.suse.com/show_bug.cgi?id=1205597
Reported-by: Richard Palethorpe <richard.palethorpe@suse.com>
Tested-by: Petr Vorel <petr.vorel@suse.com>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: Max Staudt <max@enpas.org>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Reviewed-by: Max Staudt <max@enpas.org>
Link: https://lore.kernel.org/all/20221201073426.17328-1-jirislaby@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/slcan/slcan-core.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index fbb34139daa1..f4db77007c13 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -864,12 +864,14 @@ static void slcan_close(struct tty_struct *tty)
 {
 	struct slcan *sl = (struct slcan *)tty->disc_data;
 
-	/* unregister_netdev() calls .ndo_stop() so we don't have to.
-	 * Our .ndo_stop() also flushes the TTY write wakeup handler,
-	 * so we can safely set sl->tty = NULL after this.
-	 */
 	unregister_candev(sl->dev);
 
+	/*
+	 * The netdev needn't be UP (so .ndo_stop() is not called). Hence make
+	 * sure this is not running before freeing it up.
+	 */
+	flush_work(&sl->tx_work);
+
 	/* Mark channel as dead */
 	spin_lock_bh(&sl->lock);
 	tty->disc_data = NULL;
-- 
2.35.1

[PATCH net 3/4] can: can327: flush TX_work on ldisc .close()

[Marc Kleine-Budde]

From: Max Staudt <max@enpas.org>

Additionally, remove it from .ndo_stop().

This ensures that the worker is not called after being freed, and that
the UART TX queue remains active to send final commands when the
netdev is stopped.

Thanks to Jiri Slaby for finding this in slcan:

  https://lore.kernel.org/linux-can/20221201073426.17328-1-jirislaby@kernel.org/

A variant of this patch for slcan, with the flush in .ndo_stop() still
present, has been tested successfully on physical hardware:

  https://bugzilla.suse.com/show_bug.cgi?id=1205597

Fixes: 43da2f07622f ("can: can327: CAN/ldisc driver for ELM327 based OBD-II adapters")
Cc: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Max Staudt <max@enpas.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Max Staudt <max@enpas.org>
Link: https://lore.kernel.org/all/20221202160148.282564-1-max@enpas.org
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/can327.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/can327.c b/drivers/net/can/can327.c
index ed3d0b8989a0..dc7192ecb001 100644
--- a/drivers/net/can/can327.c
+++ b/drivers/net/can/can327.c
@@ -796,9 +796,9 @@ static int can327_netdev_close(struct net_device *dev)
 
 	netif_stop_queue(dev);
 
-	/* Give UART one final chance to flush. */
-	clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
-	flush_work(&elm->tx_work);
+	/* We don't flush the UART TX queue here, as we want final stop
+	 * commands (like the above dummy char) to be flushed out.
+	 */
 
 	can_rx_offload_disable(&elm->offload);
 	elm->can.state = CAN_STATE_STOPPED;
@@ -1069,12 +1069,15 @@ static void can327_ldisc_close(struct tty_struct *tty)
 {
 	struct can327 *elm = (struct can327 *)tty->disc_data;
 
-	/* unregister_netdev() calls .ndo_stop() so we don't have to.
-	 * Our .ndo_stop() also flushes the TTY write wakeup handler,
-	 * so we can safely set elm->tty = NULL after this.
-	 */
+	/* unregister_netdev() calls .ndo_stop() so we don't have to. */
 	unregister_candev(elm->dev);
 
+	/* Give UART one final chance to flush.
+	 * No need to clear TTY_DO_WRITE_WAKEUP since .write_wakeup() is
+	 * serialised against .close() and will not be called once we return.
+	 */
+	flush_work(&elm->tx_work);
+
 	/* Mark channel as dead */
 	spin_lock_bh(&elm->lock);
 	tty->disc_data = NULL;
-- 
2.35.1

[PATCH net 4/4] can: esd_usb: Allow REC and TEC to return to zero

[Marc Kleine-Budde]

From: Frank Jungclaus <frank.jungclaus@esd.eu>

We don't get any further EVENT from an esd CAN USB device for changes
on REC or TEC while those counters converge to 0 (with ecc == 0). So
when handling the "Back to Error Active"-event force txerr = rxerr =
0, otherwise the berr-counters might stay on values like 95 forever.

Also, to make life easier during the ongoing development a
netdev_dbg() has been introduced to allow dumping error events send by
an esd CAN USB device.

Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
Signed-off-by: Frank Jungclaus <frank.jungclaus@esd.eu>
Link: https://lore.kernel.org/all/20221130202242.3998219-2-frank.jungclaus@esd.eu
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/usb/esd_usb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 81b88e9e5bdc..42323f5e6f3a 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -234,6 +234,10 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 		u8 rxerr = msg->msg.rx.data[2];
 		u8 txerr = msg->msg.rx.data[3];
 
+		netdev_dbg(priv->netdev,
+			   "CAN_ERR_EV_EXT: dlc=%#02x state=%02x ecc=%02x rec=%02x tec=%02x\n",
+			   msg->msg.rx.dlc, state, ecc, rxerr, txerr);
+
 		skb = alloc_can_err_skb(priv->netdev, &cf);
 		if (skb == NULL) {
 			stats->rx_dropped++;
@@ -260,6 +264,8 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 				break;
 			default:
 				priv->can.state = CAN_STATE_ERROR_ACTIVE;
+				txerr = 0;
+				rxerr = 0;
 				break;
 			}
 		} else {
-- 
2.35.1