RE: [PATCH] usb/core: fix NULL pointer dereference inrecursively_mark_NOTATTACHED

From: Du, ChangbinX
Date: Tue Jan 07 2014 - 04:16:59 EST

> > Changbin, after looking more closely I realized there was a second
> > aspect to this race: recursively_mark_NOTATTACHED uses hub->ports[i]
> > while hub_disconnect removes the port devices. You ought to be able
> > to cause an oops by inserting a delay just after the loop where
> > usb_hub_remove_port_device is called.
> >
> > The updated patch below should fix both problems. Can you test it?
> >
> > Alan Stern
> >
> Ok, I'll test it today or tomorrow. Please wait my response.

Alan, I cannot cause a panic after inserting a delay just after
usb_hub_remove_port_device is called, even move the delay after
kfree(hub->ports). recursively_mark_NOTATTACHED will not access
hub->ports[i] since maxchild has been set to 0.

Alan, I think your last patch can fix this issue.
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