• Alan Stern's avatar
    USB: fix crash during hotplug of PCI USB controller card · a2ff864b
    Alan Stern authored
    The code in hcd-pci.c that matches up EHCI controllers with their
    companion UHCI or OHCI controllers assumes that the private drvdata
    fields don't get set too early.  However, it turns out that this field
    gets set by usb_create_hcd(), before hcd-pci expects it, and this can
    result in a crash when two controllers are probed in parallel (as can
    happen when a new controller card is hotplugged).
    
    The companions_rwsem lock was supposed to prevent this sort of thing,
    but usb_create_hcd() is called outside the scope of the rwsem.
    
    A simple solution is to check that the root-hub pointer has been
    initialized as well as the drvdata field.  This doesn't happen until
    usb_add_hcd() is called; that call and the check are both protected by
    the rwsem.
    
    This patch should be applied to stable kernels from 3.10 onward.
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Reported-by: default avatarStefani Seibold <stefani@seibold.net>
    Tested-by: default avatarStefani Seibold <stefani@seibold.net>
    CC: <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    a2ff864b
hcd-pci.c 17.4 KB