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Date:   Fri, 14 May 2021 09:41:38 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Hayes Wang <hayeswang@realtek.com>
Cc:     Alan Stern <stern@rowland.harvard.edu>,
        syzbot <syzbot+95afd23673f5dd295c57@syzkaller.appspotmail.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "syzkaller-bugs@googlegroups.com" <syzkaller-bugs@googlegroups.com>,
        nic_swsd <nic_swsd@realtek.com>
Subject: Re: [syzbot] WARNING in rtl8152_probe
Message-ID: <20210514064138.GA1955@kadam>
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 <20210513142552.GA967812@rowland.harvard.edu>
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On Fri, May 14, 2021 at 02:58:00AM +0000, Hayes Wang wrote:
> Alan Stern <stern@rowland.harvard.edu>
> > Sent: Thursday, May 13, 2021 10:26 PM
> [...]
> > Syzbot doesn't test real devices.  It tests emulations, and the emulated
> > devices usually behave very strangely and in very peculiar and
> > unexpected ways, so as to trigger bugs in the kernel.  That's why the
> > USB devices you see in syzbot logs usually have bizarre descriptors.
> 
> Do you mean I have to debug for a device which doesn't exist?
> I don't understand why I must consider a fake device
> which provide unexpected USB descriptor deliberately?

Imagine you are at a conference and two people sit down next to you, one
on either side.  The one accidentally spills coffee on your lap.  The
other plugs in a USB device to your laptop.  Now you are infected with
spyware.

https://elie.net/blog/security/what-are-malicious-usb-keys-and-how-to-create-a-realistic-one/

regards,
dan carpenter