netdev - Re: [PATCH V3] usbnet: Prevents free active kevent

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Message-ID: <20251022022937.1799714-1-lizhi.xu@windriver.com>
Date: Wed, 22 Oct 2025 10:29:37 +0800
From: Lizhi Xu <lizhi.xu@...driver.com>
To: <kuba@...nel.org>
CC: <ahmed.zaki@...el.com>, <aleksander.lobakin@...el.com>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <horms@...nel.org>,
        <kuniyu@...zon.com>, <linux-kernel@...r.kernel.org>,
        <lizhi.xu@...driver.com>, <netdev@...r.kernel.org>,
        <pabeni@...hat.com>, <samsun1006219@...il.com>, <sdf@...ichev.me>,
        <syzkaller-bugs@...glegroups.com>, <syzkaller@...glegroups.com>
Subject: Re: [PATCH V3] usbnet: Prevents free active kevent

On Tue, 21 Oct 2025 18:32:52 -0700, Jakub Kicinski wrote:
> > --- a/drivers/net/usb/usbnet.c
> > +++ b/drivers/net/usb/usbnet.c
> > @@ -1672,6 +1672,9 @@ void usbnet_disconnect (struct usb_interface *intf)
> >  	usb_free_urb(dev->interrupt);
> >  	kfree(dev->padding_pkt);
> >  
> > +	cancel_work_sync(&dev->kevent);
> > +	timer_delete_sync(&dev->delay);
> > +
> >  	free_netdev(net);
> 
> Is this the best spot to place the cancel?
> I think it may be better right after unregister_netdev().
> I haven't analyze this driver too closely but for example since
> kevent may call the sub-driver having it running after we already
> called dev->driver_info->unbind() seems risky.
I agree with your analysis. I'll update the patch and release a new version.

BR,
Lizhi