From: Dmitry Vyukov <dvyukov@google.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Johan Hovold <johan@kernel.org>,
syzbot <syzbot+72af3105289dcb4c055b@syzkaller.appspotmail.com>,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, mathias.nyman@linux.intel.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in do_proc_control/usb_submit_urb
Date: Mon, 12 Jul 2021 18:24:43 +0200 [thread overview]
Message-ID: <CACT4Y+biD8AdKncmvqmaz3dytV-zoeo==rdkTSJvaZ9=RUs=UA@mail.gmail.com> (raw)
In-Reply-To: <20210712161445.GA321728@rowland.harvard.edu>
On Mon, 12 Jul 2021 at 18:14, Alan Stern <stern@rowland.harvard.edu> wrote:
> > > > > Hello,
> > > > >
> > > > > syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> > > > > WARNING in do_proc_control/usb_submit_urb
> >
> > > > I don't get this. It shouldn't be possible. The fact that the
> > > > direction bit is set in both bRequestType and pipe means that the URB
> > > > was submitted as a control-IN but had length 0. But the patch addresses
> > > > exactly that case:
> > > >
> > > > --- usb-devel.orig/drivers/usb/core/devio.c
> > > > +++ usb-devel/drivers/usb/core/devio.c
> > > > @@ -1133,7 +1133,7 @@ static int do_proc_control(struct usb_de
> > > > "wIndex=%04x wLength=%04x\n",
> > > > ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
> > > > ctrl->wIndex, ctrl->wLength);
> > > > - if (ctrl->bRequestType & 0x80) {
> > > > + if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength) {
> > > > pipe = usb_rcvctrlpipe(dev, 0);
> > > > snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT, NULL, 0);
> > > >
> > > > and causes the kernel to handle it as a control-OUT instead.
> > > >
> > > > Johan, any ideas?
> > >
> > > Did syzbot actually test the patch? I can't see how the direction bit of
> > > the pipe argument can be set with the above applied either.
> >
> > It looks like the second patch you submitted was hand-edited and still
> > quoted.
> >
> > And looking at the dashboard it seems like no patch was applied for your
> > second test attempt:
> >
> > https://syzkaller.appspot.com/bug?extid=72af3105289dcb4c055b
>
> Yes, that explains it. Funny how easy it is to miss those "> "
> markings -- you just get too used to them.
>
> > I've been bitten by something like this before when erroneously thinking
> > that a test command could be submitted as a reply to a patch.
> >
> > Perhaps the report mail could include the patch tested or something so
> > we don't spend time investigating syzbot interface failures.
>
> Good idea.
The email always include the patch tested (as syzbot parsed it), see
e.g. earlier reply in this thread:
https://lore.kernel.org/lkml/00000000000074f06705c6ccd2a4@google.com/
> Anyway, here's the patch again, this time properly formatted. Hopefully
> now it will work.
syzbot parsed this patch successfully:
https://syzkaller.appspot.com/bug?extid=72af3105289dcb4c055b
> Alan Stern
>
>
> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git ee268dee
>
> Index: usb-devel/drivers/usb/core/devio.c
> ===================================================================
> --- usb-devel.orig/drivers/usb/core/devio.c
> +++ usb-devel/drivers/usb/core/devio.c
> @@ -1133,7 +1133,7 @@ static int do_proc_control(struct usb_de
> "wIndex=%04x wLength=%04x\n",
> ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
> ctrl->wIndex, ctrl->wLength);
> - if (ctrl->bRequestType & 0x80) {
> + if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength) {
> pipe = usb_rcvctrlpipe(dev, 0);
> snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT, NULL, 0);
>
>
> --
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> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20210712161445.GA321728%40rowland.harvard.edu.
next prev parent reply other threads:[~2021-07-12 16:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-10 11:11 [syzbot] WARNING in do_proc_control/usb_submit_urb syzbot
2021-07-10 14:50 ` Alan Stern
2021-07-10 22:58 ` syzbot
2021-07-11 0:36 ` Alan Stern
2021-07-11 15:53 ` Alan Stern
2021-07-11 16:07 ` syzbot
2021-07-12 14:00 ` Alan Stern
2021-07-12 15:29 ` Johan Hovold
2021-07-12 15:50 ` Johan Hovold
2021-07-12 16:14 ` Alan Stern
2021-07-12 16:24 ` Dmitry Vyukov [this message]
2021-07-12 18:48 ` Alan Stern
2021-07-15 7:19 ` Dmitry Vyukov
2021-07-12 16:32 ` syzbot
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