From: Sean Young <sean@mess.org>
To: Oliver Neukum <oneukum@suse.com>
Cc: linux-media@vger.kernel.org, linux-usb@vger.kernel.org,
Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jon Rhees <support@usbuirt.com>
Subject: Re: [PATCH v2 2/3] media: rc: new driver for USB-UIRT device
Date: Thu, 6 May 2021 10:07:33 +0100 [thread overview]
Message-ID: <20210506090733.GA1483@gofer.mess.org> (raw)
In-Reply-To: <72f835c84c16b455222fece3bb3527f16ad965be.camel@suse.com>
Hi Oliver,
On Thu, May 06, 2021 at 10:27:21AM +0200, Oliver Neukum wrote:
> Am Mittwoch, den 05.05.2021, 22:57 +0100 schrieb Sean Young:
> > +static void uirt_disconnect(struct usb_interface *intf)
> > +{
> > + struct uirt *ir = usb_get_intfdata(intf);
> > +
> > + rc_unregister_device(ir->rc);
> > + usb_set_intfdata(intf, NULL);
> > + usb_kill_urb(ir->urb_out);
> > + usb_free_urb(ir->urb_out);
> > + usb_kill_urb(ir->urb_in);
> > + usb_free_urb(ir->urb_in);
> > + kfree(ir->in);
> > + kfree(ir->out);
> > + kfree(ir);
> > +}
>
> Hi,
>
> almost. Going through this again, it looks like you have a race
> condition here.
>
> CPU A CPU B
>
> usb_kill_urb(ir->urb_out);
> usb_free_urb(ir->urb_out);
>
> uirt_in_callback()
> uirt_response(struct uirt *uirt, u32 len)
> err = usb_submit_urb(uirt->urb_out, GFP_ATOMIC);
>
> BANG, you are using freeed memory
Nice catch, I had missed this. I'll send out a v3 with this fixed.
This needs fixing, for sure. Having said that, once we are in the disconnect
handler aren't all urbs/endpoints disabled in usb_disable_interface()? Does
this mean the usb_kill_urb() are superfluous?
Thanks,
Sean
next prev parent reply other threads:[~2021-05-06 9:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 21:57 [PATCH v2 0/3] IR driver for USB-UIRT device Sean Young
2021-05-05 21:57 ` [PATCH v2 1/3] USB: serial: move ftdi_sio.h into include directories Sean Young
2021-05-05 21:57 ` [PATCH v2 2/3] media: rc: new driver for USB-UIRT device Sean Young
2021-05-06 8:27 ` Oliver Neukum
2021-05-06 9:07 ` Sean Young [this message]
2021-05-05 21:57 ` [PATCH v2 3/3] USB: serial: blacklist USB-UIRT when driver is selected Sean Young
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