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From: Jiri Kosina <jikos@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: syzbot <syzbot+9b57a46bf1801ce2a2ca@syzkaller.appspotmail.com>,
	benjamin.tissoires@redhat.com, linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org, 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 13:53:56 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.YFH.7.76.2108241351490.15313@cbobk.fhfr.pm> (raw)
In-Reply-To: <20210820140620.GA35867@rowland.harvard.edu>

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?

Thanks,

-- 
Jiri Kosina
SUSE Labs


  reply	other threads:[~2021-08-24 11:54 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 [this message]
2021-08-24 12:34                   ` Benjamin Tissoires
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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