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From: Alan Stern <stern@rowland.harvard.edu>
To: Andrey Konovalov <andreyknvl@google.com>,
	Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	USB list <linux-usb@vger.kernel.org>
Subject: UDC hardware for fuzzing [was: Re: INFO: task hung in usb_kill_urb]
Date: Fri, 19 Apr 2019 14:36:38 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1904191429230.1406-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <CAAeHK+zCwXpAb02vaPuanStYCp_x8g92HDEvm_LTN_F+Y_wOfQ@mail.gmail.com>

On Wed, 17 Apr 2019, Andrey Konovalov wrote:

> On Tue, Apr 16, 2019 at 8:25 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > On Tue, 16 Apr 2019, syzbot wrote:
> >
> > > Hello,
> > >
> > > syzbot has tested the proposed patch but the reproducer still triggered
> > > crash:
> > > INFO: task hung in usb_kill_urb
> >
> > Okay, I think I found the problem.  dummy-hcd doesn't check for
> > unsupported speeds until it is too late.  Andrey, what values does your
> > usb-fuzzer gadget driver set for its max_speed field?
> 
> It's passed from userspace without any validation :( I'll fix this!
> Thanks for looking into it!
> 
> I wonder why other people saw this hang as well, they didn't use the
> dummy hcd module for sure. I guess there are might be other reasons.

Unquestionably it would be for other reasons.  usb_kill_urb() is a 
host-side routine, not used by gadget drivers.  If it fails, the reason 
lies in host controller driver.  And if people aren't using dummy-hcd 
then they must be using a different host controller driver.

Is there any chance you could get hold of a USB device controller for 
more fuzzing tests?  With it, you could test other parts of the USB 
stack: the UDC driver for whatever hardware you get, and the host 
controller driver for whatever you plug the UDC into.

I don't know what types of UDC are readily available for the type of
computer syzkaller uses.  Perhaps Felipe or other people on the mailing
list will have some suggestions.

Alan Stern


WARNING: multiple messages have this Message-ID (diff)
From: Alan Stern <stern@rowland.harvard.edu>
To: Andrey Konovalov <andreyknvl@google.com>,
	Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	USB list <linux-usb@vger.kernel.org>
Subject: INFO: task hung in usb_kill_urb
Date: Fri, 19 Apr 2019 14:36:38 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1904191429230.1406-100000@iolanthe.rowland.org> (raw)

On Wed, 17 Apr 2019, Andrey Konovalov wrote:

> On Tue, Apr 16, 2019 at 8:25 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > On Tue, 16 Apr 2019, syzbot wrote:
> >
> > > Hello,
> > >
> > > syzbot has tested the proposed patch but the reproducer still triggered
> > > crash:
> > > INFO: task hung in usb_kill_urb
> >
> > Okay, I think I found the problem.  dummy-hcd doesn't check for
> > unsupported speeds until it is too late.  Andrey, what values does your
> > usb-fuzzer gadget driver set for its max_speed field?
> 
> It's passed from userspace without any validation :( I'll fix this!
> Thanks for looking into it!
> 
> I wonder why other people saw this hang as well, they didn't use the
> dummy hcd module for sure. I guess there are might be other reasons.

Unquestionably it would be for other reasons.  usb_kill_urb() is a 
host-side routine, not used by gadget drivers.  If it fails, the reason 
lies in host controller driver.  And if people aren't using dummy-hcd 
then they must be using a different host controller driver.

Is there any chance you could get hold of a USB device controller for 
more fuzzing tests?  With it, you could test other parts of the USB 
stack: the UDC driver for whatever hardware you get, and the host 
controller driver for whatever you plug the UDC into.

I don't know what types of UDC are readily available for the type of
computer syzkaller uses.  Perhaps Felipe or other people on the mailing
list will have some suggestions.

Alan Stern

  reply	other threads:[~2019-04-19 18:36 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAAeHK+wDEOpkuh0+OmPra3Yu8ri-8As82CyZ-1KyYC62AJkj1Q@mail.gmail.com>
2019-04-16 15:44 ` INFO: task hung in usb_kill_urb Alan Stern
2019-04-16 15:44   ` Alan Stern
2019-04-16 16:19   ` syzbot
2019-04-16 16:19     ` syzbot
2019-04-16 18:25     ` Alan Stern
2019-04-16 18:25       ` Alan Stern
2019-04-16 19:03       ` syzbot
2019-04-16 19:03         ` syzbot
2019-04-16 21:14         ` Alan Stern
2019-04-16 21:14           ` Alan Stern
2019-04-16 21:53           ` syzbot
2019-04-16 21:53             ` syzbot
2019-04-17 19:09             ` Alan Stern
2019-04-17 19:09               ` Alan Stern
2019-04-17 19:56               ` syzbot
2019-04-17 19:56                 ` syzbot
2019-04-18 12:21               ` Andrey Konovalov
2019-04-18 12:21                 ` Andrey Konovalov
2019-04-17 11:16       ` Andrey Konovalov
2019-04-17 11:16         ` Andrey Konovalov
2019-04-19 18:36         ` Alan Stern [this message]
2019-04-19 18:36           ` Alan Stern
2019-04-23 12:44           ` UDC hardware for fuzzing [was: Re: INFO: task hung in usb_kill_urb] Andrey Konovalov
2019-04-23 12:44             ` INFO: task hung in usb_kill_urb Andrey Konovalov
2019-04-18 17:12 USB: dummy-hcd: Fix failure to give back unlinked URBs Alan Stern
2019-04-18 17:12 ` [PATCH] " Alan Stern

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