linux-kernel - Re: KASAN: use-after-free Read in si470x_int_in

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Date:   Fri, 22 Nov 2019 20:00:56 +0100
From:   Oliver Neukum <oneukum@...e.com>
To:     Alan Stern <stern@...land.harvard.edu>,
        syzbot <syzbot+9ca7a12fd736d93e0232@...kaller.appspotmail.com>
Cc:     andreyknvl@...gle.com, hverkuil@...all.nl,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-usb@...r.kernel.org, mchehab@...nel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: KASAN: use-after-free Read in si470x_int_in_callback (2)

Am Freitag, den 22.11.2019, 10:35 -0500 schrieb Alan Stern:
> On Fri, 22 Nov 2019, syzbot wrote:
> 
> > Hello,
> > 
> > syzbot has tested the proposed patch but the reproducer still triggered  
> > crash:
> > INFO: rcu detected stall in dummy_timer
> > 
> > radio-si470x 1-1:0.0: non-zero urb status (-71)
> > radio-si470x 4-1:0.0: non-zero urb status (-71)
> > radio-si470x 3-1:0.0: non-zero urb status (-71)
> 
> Oliver:
> 
> The reason for this stall is because the driver goes into a tight
> resubmit loop when the interrupt URB completes with an unrecognized
> error status.  Instead, the driver should log an error message and
> avoid resubmitting.  Error recovery can be done at a higher level.
> 
> In other words, change the
> 
> 			goto resubmit; /* Maybe we can recover. */
> 
> line in the completion handler into a return.

I thought so, too. That is why I poisoned the URB. Am I dense?

	Regards
		Oliver