From: Lizhi Xu Date: Wed, 22 Oct 2025 02:40:07 +0000 (+0800) Subject: usbnet: Prevents free active kevent X-Git-Tag: v6.18-rc4~24^2~31 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=420c84c330d1688b8c764479e5738bbdbf0a33de;p=thirdparty%2Fkernel%2Flinux.git usbnet: Prevents free active kevent The root cause of this issue are: 1. When probing the usbnet device, executing usbnet_link_change(dev, 0, 0); put the kevent work in global workqueue. However, the kevent has not yet been scheduled when the usbnet device is unregistered. Therefore, executing free_netdev() results in the "free active object (kevent)" error reported here. 2. Another factor is that when calling usbnet_disconnect()->unregister_netdev(), if the usbnet device is up, ndo_stop() is executed to cancel the kevent. However, because the device is not up, ndo_stop() is not executed. The solution to this problem is to cancel the kevent before executing free_netdev(). Fixes: a69e617e533e ("usbnet: Fix linkwatch use-after-free on disconnect") Reported-by: Sam Sun Closes: https://syzkaller.appspot.com/bug?extid=8bfd7bcc98f7300afb84 Signed-off-by: Lizhi Xu Link: https://patch.msgid.link/20251022024007.1831898-1-lizhi.xu@windriver.com Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index bf01f2728531..697cd9d866d3 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -1659,6 +1659,8 @@ void usbnet_disconnect (struct usb_interface *intf) net = dev->net; unregister_netdev (net); + cancel_work_sync(&dev->kevent); + while ((urb = usb_get_from_anchor(&dev->deferred))) { dev_kfree_skb(urb->context); kfree(urb->sg);