Re: [PATCH] usb: hub: fix panic caused by NULL bos pointer during reset device

[Greg KH]

On Wed, Apr 27, 2016 at 09:35:57AM -0400, Tony Battersby wrote:
> On 04/26/2016 10:53 PM, Du, Changbin wrote:
> >> On Tue, Mar 08, 2016 at 05:15:17PM +0800, changbin.du@xxxxxxxxx wrote:
> >>> From: "Du, Changbin" <changbin.du@xxxxxxxxx>
> >>>
> >>> This is a reworked patch based on reverted commit d8f00cd685f5 ("usb:
> >>> hub: do not clear BOS field during reset device").
> >>>
> >>> The privious one caused double mem-free if run to re_enumerate label.
> >>> New patch title changed to distinguish from old one. And I have tested
> >>> it with memory debugging options.
> >>>
> >>> In function usb_reset_and_verify_device, the old BOS descriptor may
> >>> still be used before allocating a new one. (usb_disable_lpm function
> >>> uses it under the situation that it fails at usb_disable_link_state.)
> >>> So we cannot set the udev->bos to NULL before that, just keep what it
> >>> was. It will be overwrite when allocating a new one.
> >>>
> >>> How to reproduce:
> >>> 1. connect one usb3 hub to xhci port.
> >>> 2. connect several lpm-capable super-speed usb disk to the hub.
> >>> 3. copy big files to the usb disks.
> >>> 4. disconnect the hub and repeat step 1-4.
> >>>
> >>> Crash log:
> >>> BUG: unable to handle kernel NULL pointer dereference at
> >>> 0000000000000010
> >>> IP: [<ffffffff8171f98d>] usb_enable_link_state+0x2d/0x2f0
> >>> Call Trace:
> >>> [<ffffffff8171ed5b>] ? usb_set_lpm_timeout+0x12b/0x140
> >>> [<ffffffff8171fcd1>] usb_enable_lpm+0x81/0xa0
> >>> [<ffffffff8171fdd8>] usb_disable_lpm+0xa8/0xc0
> >>> [<ffffffff8171fe1c>] usb_unlocked_disable_lpm+0x2c/0x50
> >>> [<ffffffff81723933>] usb_reset_and_verify_device+0xc3/0x710
> >>> [<ffffffff8172c4ed>] ? usb_sg_wait+0x13d/0x190
> >>> [<ffffffff81724743>] usb_reset_device+0x133/0x280
> >>> [<ffffffff8179ccd1>] usb_stor_port_reset+0x61/0x70
> >>> [<ffffffff8179cd68>] usb_stor_invoke_transport+0x88/0x520
> >>>
> >>> Signed-off-by: Du, Changbin <changbin.du@xxxxxxxxx>
> >>> ---
> >>>  drivers/usb/core/hub.c | 14 +++++++++-----
> >>>  1 file changed, 9 insertions(+), 5 deletions(-)
> >> Is this patch still needed?  I thought we had some other fix in this
> >> area...
> >>
> >> confused,
> >>
> >> greg k-h
> >>
> > Hi, Greg k-h,
> > Sorry for it confused you. This patch still need. This is same fix with
> > previous commit d8f00cd685f5 ("usb: hub: do not clear BOS field
> > during reset device"). But d8f00cd685f5 is buggy and reverted. This
> > new patch should be the final fix.
> >
> > Best Regards,
> > Du, Changbin
> >
> 
> I think Greg is referring to commit 464ad8c43a9e ("usb: core : hub: Fix
> BOS 'NULL pointer' kernel panic"), which has already been applied
> upstream.  It looks to me like that patch might have fixed the same
> problem in a different way, in which case Changbin's patch is not
> needed.  But I haven't been involved in developing or testing that
> patch, so I can't say for sure.  At the very least, 464ad8c43a9e
> conflicts with Changbin's patch.
> 
> Changbin, can you take a look at 464ad8c43a9e and see if that fixes the
> same problem that your patch did?

Given the lack of response here, I've dropped this from my queue.  If
it's still needed, someone must resend it.

thanks,

greg k-h