linux-kernel - Re: [PATCH net] net: usb: rtl8150: enable basic endpoint checking

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f099be8f-0ae0-49c7-b0bc-02770d9c1210@rowland.harvard.edu>
Date: Wed, 22 Jan 2025 10:59:33 -0500
From: Alan Stern <stern@...land.harvard.edu>
To: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
Cc: Petko Manolov <petkan@...leusys.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linux-usb@...r.kernel.org, netdev@...r.kernel.org,
	syzbot+d7e968426f644b567e31@...kaller.appspotmail.com,
	syzkaller-bugs@...glegroups.com, linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: Re: [PATCH net] net: usb: rtl8150: enable basic endpoint checking

On Wed, Jan 22, 2025 at 05:20:12AM -0800, Nikita Zhandarovich wrote:
> Hi,
> 
> On 1/22/25 04:43, Petko Manolov wrote:
> > On 25-01-22 02:42:46, Nikita Zhandarovich wrote:
> >> Syzkaller reports [1] encountering a common issue of utilizing a wrong usb
> >> endpoint type during URB submitting stage. This, in turn, triggers a warning
> >> shown below.
> > 
> > If these endpoints were of the wrong type the driver simply wouldn't work.

Better not to bind at all than to bind in a non-working way.  Especially 
when we can tell by a simple check that the device isn't what the driver 
expects.

> > The proposed change in the patch doesn't do much in terms of fixing the issue
> > (pipe 3 != type 1) and if usb_check_bulk_endpoints() fails, the driver will just
> > not probe successfully.  I don't see how this is an improvement to the current
> > situation.

It fixes the issue by preventing the driver from submitting an interrupt 
URB to a bulk endpoint or vice versa.

> > We should either spend some time fixing the "BOGUS urb xfer, pipe 3 != type 1"
> > for real or not touch anything.
> > 
> > 
> > 		Petko
> > 
> > 
> 
> Thank you for your answer, I had a couple thoughts though.
> 
> If I understand correctly (which may not be the case, of course), since
> the driver currently does not have any sanity checks for endpoints and
> URBs' pipes are initialized essentially by fixed constants (as is often
> the case), once again without any testing, then a virtual, weirdly
> constructed device, like the one made up by Syzkaller, could provide
> endpoints with contents that may cause that exact warning.
> 
> Real-life devices (with appropriate eps) would still work well and are
> in no danger, with or without the patch. And even if that warning is
> triggered, I am not certain the consequences are that severe, maybe on
> kernels with 'panic_on_warn' set, and that's another conversation.
> However, it seems that the change won't hurt either. Failing probe() in
> such situations looks to be the standard.
> 
> If my approach is flawed, I'd really appreciate some hints on how you
> would address that issue and I'd like to tackle it. I'd also ask if
> other recipients could provide some of their views on the issue, even if
> just to prove me wrong.

I agree with this approach; it seems like the best way to address this 
issue.

Alan Stern