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From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Jiri Kosina <jikos@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	syzbot <syzbot+9b57a46bf1801ce2a2ca@syzkaller.appspotmail.com>,
	"open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Linux USB Mailing List <linux-usb@vger.kernel.org>,
	mkubecek@suse.cz, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in hid_submit_ctrl/usb_submit_urb
Date: Tue, 24 Aug 2021 14:34:30 +0200	[thread overview]
Message-ID: <CAO-hwJL10rAS3BHoFOAD5evkd1zYw5ffb5u2c6uXYf9jh9jkoA@mail.gmail.com> (raw)
In-Reply-To: <nycvar.YFH.7.76.2108241351490.15313@cbobk.fhfr.pm>

On Tue, Aug 24, 2021 at 1:54 PM Jiri Kosina <jikos@kernel.org> wrote:
>
> On Fri, 20 Aug 2021, Alan Stern wrote:
>
> > > syzbot has tested the proposed patch and the reproducer did not trigger any issue:
> >
> > That's good to know.  Still, I suspect there's a better way of handling
> > this condition.
> >
> > In particular, does it make sense to accept descriptors for input or
> > feature reports with length zero?  I can't imagine what good such
> > reports would do.
>
> I quickly went through drivers + some hidraw users, and can't spot any use
> case for it.
>
> > On the other hand, I'm not familiar enough with the code to know the
> > right way to reject these descriptors and reports.  It looks like the
> > HID subsystem was not designed with this sort of check in mind.
> >
> > Benjamin and Jiri, what do you think?  Is it okay to allow descriptors
> > for zero-length reports and just pretend they have length 1 (as the
> > patch tested by syzbot did), or should we instead reject them during
> > probing?
>
> I think it's a good band-aid for 5.14 (or 5.14-stable if we don't make
> it), and if it turns out to break something (which I don't expect), than
> we can look into rejecting already during probe.
>
> Benjamin, is there a way to run this quickly through your HID regression
> testing machinery?

[Sorry, on holidays since last week until the end of this one]

This patch addresses usbhid, so I don't have tests on this unless I
manually plug mice, keyboards or random input hardware :(

I can try to quickly get a logitech dj receiver test that should use
heavily control endpoints, and probably get a Wacom test. No guarantee
I can get it today though.

Cheers,
Benjamin

>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs
>


  reply	other threads:[~2021-08-24 12:34 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-18 15:46 syzbot
2021-08-18  9:14 ` syzbot
2021-08-18 18:49   ` Alan Stern
2021-08-18 20:13     ` syzbot
2021-08-19 15:26       ` Alan Stern
2021-08-19 17:35         ` syzbot
2021-08-19 19:53           ` Alan Stern
2021-08-20  0:40             ` syzbot
2021-08-20 14:06               ` Alan Stern
2021-08-24 11:53                 ` Jiri Kosina
2021-08-24 12:34                   ` Benjamin Tissoires [this message]
2021-08-31  9:51                   ` Benjamin Tissoires
2021-08-31 13:34                     ` Alan Stern
2021-08-31 19:53                       ` Jiri Kosina
2021-09-01 15:38                     ` Alan Stern
2021-09-01 15:51                       ` Michal Kubecek
2021-08-24 11:50             ` Michal Kubecek
2021-08-30 19:22             ` Oleksandr Natalenko
2021-08-18 19:01   ` Alan Stern
2021-08-18 19:39 ` syzbot

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