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Subject: Re: [syzbot] WARNING in rtl8152_probe
From:   Oliver Neukum <oneukum@suse.com>
To:     Hayes Wang <hayeswang@realtek.com>,
        Alan Stern <stern@rowland.harvard.edu>
Cc:     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>
Date:   Mon, 17 May 2021 12:00:19 +0200
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Am Montag, den 17.05.2021, 01:01 +0000 schrieb Hayes Wang:
> Alan Stern <stern@rowland.harvard.edu>
> > Sent: Friday, May 14, 2021 11:33 PM

> > So if a peculiar emulated device created by syzbot is capable of
> > crashing the driver, then somewhere there is a bug which needs to
> > be
> > fixed.  It's true that fixing all these bugs might not protect
> > against a
> > malicious device which deliberately behaves in an apparently
> > reasonable
> > manner.  But it does reduce the attack surface.
> 
> Thanks for your response.
> I will add some checks.

Hi,

the problem in this particular case is in
static bool rtl_vendor_mode(struct usb_interface *intf)
which accepts any config number. It needs to bail out
if you find config #0 to be what the descriptors say,
treating that as an unrecoverable error.

	Regards
		Oliver