On Tue, Aug 20, 2013 at 02:18:57PM -0400, Alan Stern wrote: > On Tue, 20 Aug 2013, Krzysztof Mazur wrote: > > > Ignoring usb_hub_create_port_device() errors cause later NULL pointer > > deference when uninitialized hub->ports[i] entries are dereferenced > > after port memory allocation error. > > > > Signed-off-by: Krzysztof Mazur <krzysiek@xxxxxxxxxxxx> > > --- > > I'm not sure if failing in that case is a good idea, but other solutions > > are more complex. > > > > I tried also changing hdev->maxchild and skiping initialization > > of later ports, but it didn't work because in some cases > > hub->descriptor->bNbrPorts is used instead of hdev->maxchild. > > With simulated usb_hub_create_port_device() failure I have an Oops > > in hub_power_on(). > > I think this patch is correct. However, we also should change the > other places that refer to bNbrPorts; make them use maxchild instead. Ok, I can try to catch all such cases and fix problems with maxchild < bNBrPorts, but I think that changing bNBrPorts to maxchild might be not enough. For instance: for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++) if (hub->ports[port1 - 1]->power_is_on) set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER); else usb_clear_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER); in hub_power_on() should be probably changed to something like: for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++) if (hub->ports[port1 - 1] && hub->ports[port1 - 1]->power_is_on) set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER); else usb_clear_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER); to disable uninitialized ports. > > > Another possible solution is allowing for uninitialized ports and > > checking for hub->ports[i] == NULL. > > No, if we can't allocate memory for all the ports then the whole thing > should fail. The usb_hub_create_port_device() might fail also in case of device_add() error. > > Alan Stern Thanks, Krzysiek -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
