The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 04e906839a053f092ef53f4fb2d610983412b904 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024100138-ramp-unnatural-4b06@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

04e906839a05 ("usbnet: fix cyclical race on disconnect with work queue") a69e617e533e ("usbnet: Fix linkwatch use-after-free on disconnect") 478890682ff7 ("usbnet: add usbnet_event_names[] for kevent") 956baa99571b ("usbnet: add method for reporting speed without MII") 77651900cede ("usbnet: add _mii suffix to usbnet_set/get_link_ksettings")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 04e906839a053f092ef53f4fb2d610983412b904 Mon Sep 17 00:00:00 2001 From: Oliver Neukum oneukum@suse.com Date: Thu, 19 Sep 2024 14:33:42 +0200 Subject: [PATCH] usbnet: fix cyclical race on disconnect with work queue

The work can submit URBs and the URBs can schedule the work. This cycle needs to be broken, when a device is to be stopped. Use a flag to do so. This is a design issue as old as the driver.

Signed-off-by: Oliver Neukum oneukum@suse.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") CC: stable@vger.kernel.org Link: https://patch.msgid.link/20240919123525.688065-1-oneukum@suse.com Signed-off-by: Paolo Abeni pabeni@redhat.com

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 18eb5ba436df..2506aa8c603e 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -464,10 +464,15 @@ static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb, void usbnet_defer_kevent (struct usbnet *dev, int work) { set_bit (work, &dev->flags); - if (!schedule_work (&dev->kevent)) - netdev_dbg(dev->net, "kevent %s may have been dropped\n", usbnet_event_names[work]); - else - netdev_dbg(dev->net, "kevent %s scheduled\n", usbnet_event_names[work]); + if (!usbnet_going_away(dev)) { + if (!schedule_work(&dev->kevent)) + netdev_dbg(dev->net, + "kevent %s may have been dropped\n", + usbnet_event_names[work]); + else + netdev_dbg(dev->net, + "kevent %s scheduled\n", usbnet_event_names[work]); + } } EXPORT_SYMBOL_GPL(usbnet_defer_kevent);

@@ -535,7 +540,8 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags) tasklet_schedule (&dev->bh); break; case 0: - __usbnet_queue_skb(&dev->rxq, skb, rx_start); + if (!usbnet_going_away(dev)) + __usbnet_queue_skb(&dev->rxq, skb, rx_start); } } else { netif_dbg(dev, ifdown, dev->net, "rx: stopped\n"); @@ -843,9 +849,18 @@ int usbnet_stop (struct net_device *net)

/* deferred work (timer, softirq, task) must also stop */ dev->flags = 0; - del_timer_sync (&dev->delay); - tasklet_kill (&dev->bh); + del_timer_sync(&dev->delay); + tasklet_kill(&dev->bh); cancel_work_sync(&dev->kevent); + + /* We have cyclic dependencies. Those calls are needed + * to break a cycle. We cannot fall into the gaps because + * we have a flag + */ + tasklet_kill(&dev->bh); + del_timer_sync(&dev->delay); + cancel_work_sync(&dev->kevent); + if (!pm) usb_autopm_put_interface(dev->intf);

@@ -1171,7 +1186,8 @@ usbnet_deferred_kevent (struct work_struct *work) status); } else { clear_bit (EVENT_RX_HALT, &dev->flags); - tasklet_schedule (&dev->bh); + if (!usbnet_going_away(dev)) + tasklet_schedule(&dev->bh); } }

@@ -1196,7 +1212,8 @@ usbnet_deferred_kevent (struct work_struct *work) usb_autopm_put_interface(dev->intf); fail_lowmem: if (resched) - tasklet_schedule (&dev->bh); + if (!usbnet_going_away(dev)) + tasklet_schedule(&dev->bh); } }

@@ -1559,6 +1576,7 @@ static void usbnet_bh (struct timer_list *t) } else if (netif_running (dev->net) && netif_device_present (dev->net) && netif_carrier_ok(dev->net) && + !usbnet_going_away(dev) && !timer_pending(&dev->delay) && !test_bit(EVENT_RX_PAUSED, &dev->flags) && !test_bit(EVENT_RX_HALT, &dev->flags)) { @@ -1606,6 +1624,7 @@ void usbnet_disconnect (struct usb_interface *intf) usb_set_intfdata(intf, NULL); if (!dev) return; + usbnet_mark_going_away(dev);

xdev = interface_to_usbdev (intf);

diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index 9f08a584d707..0b9f1e598e3a 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -76,8 +76,23 @@ struct usbnet { # define EVENT_LINK_CHANGE 11 # define EVENT_SET_RX_MODE 12 # define EVENT_NO_IP_ALIGN 13 +/* This one is special, as it indicates that the device is going away + * there are cyclic dependencies between tasklet, timer and bh + * that must be broken + */ +# define EVENT_UNPLUG 31 };

+static inline bool usbnet_going_away(struct usbnet *ubn) +{ + return test_bit(EVENT_UNPLUG, &ubn->flags); +} + +static inline void usbnet_mark_going_away(struct usbnet *ubn) +{ + set_bit(EVENT_UNPLUG, &ubn->flags); +} + static inline struct usb_driver *driver_of(struct usb_interface *intf) { return to_usb_driver(intf->dev.driver);