Date: Sun, 20 Mar 2016 19:00:31 +0800
From: Peter Chen <hzpeterchen@gmail.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Nicolai Stange <nicstange@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Chen <peter.chen@freescale.com>,
        Philipp Zabel <p.zabel@pengutronix.de>, Rob Herring <robh@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Geliang Tang <geliangtang@163.com>,
        Stefan Koch <stefan.koch10@gmail.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Oliver Neukum <oneukum@suse.com>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] usb/core: usb_alloc_dev(): fix setting of ->portnum
Message-ID: <20160320110031.GA30461@shlinux2.ap.freescale.net>
References: <1458255182-16217-1-git-send-email-nicstange@gmail.com>
 <Pine.LNX.4.44L0.1603181013020.1866-100000@iolanthe.rowland.org>
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On Fri, Mar 18, 2016 at 10:13:34AM -0400, Alan Stern wrote:
> On Thu, 17 Mar 2016, Nicolai Stange wrote:
> 
> > With commit 69bec7259853 ("USB: core: let USB device know device node"),
> > the port1 argument of usb_alloc_dev() gets overwritten as follows:
> > 
> >   ... usb_alloc_dev(..., unsigned port1)
> >   {
> >     ...
> >     if (!parent->parent) {
> >       port1 = usb_hcd_find_raw_port_number(..., port1);
> >     }
> >     ...
> >   }
> > 
> > Later on, this now overwritten port1 gets assigned to ->portnum:
> > 
> >   dev->portnum = port1;
> > 
> > However, since xhci_find_raw_port_number() isn't idempotent, the
> > aforementioned commit causes a number of KASAN splats like the following:
> 
> ...
> 
> > Fix this by not overwriting the port1 argument in usb_alloc_dev(), but
> > storing the raw port number as required by OF in an additional variable,
> > raw_port.
> > 
> > Fixes: 69bec7259853 ("USB: core: let USB device know device node")
> > Signed-off-by: Nicolai Stange <nicstange@gmail.com>
> > ---
> >  Applicable to linux-next-20160317
> > 
> >  Changes to v1:
> >  - Initialize raw_port with port1
> 
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> 

Thanks for fixing it in time, you are right. My patch would let the
device logical port number equals to device raw port number, but it
is wrong for xhci.

-- 

Best Regards,
Peter Chen