On Fri, Jan 17, 2020 at 03:41:50PM +0800, Macpaul Lin wrote: > According to NULL pointer fix: https://tinyurl.com/uqft5ra > xhci: Fix NULL pointer dereference with xhci_irq() for shared_hcd > The similar issue has also been found in QC activities in Mediatek. > > Here quote the description from the referenced patch as follows. > "Commit ("f068090426ea xhci: Fix leaking USB3 shared_hcd > at xhci removal") sets xhci_shared_hcd to NULL without > stopping xhci host. This results into a race condition > where shared_hcd (super speed roothub) related interrupts > are being handled with xhci_irq happens when the > xhci_plat_remove is called and shared_hcd is set to NULL. > Fix this by setting the shared_hcd to NULL only after the > controller is halted and no interrupts are generated." > > Signed-off-by: Sriharsha Allenki <sallenki@xxxxxxxxxxxxxx> > Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx> > --- > drivers/usb/host/xhci-mtk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c > index b18a6baef204..c227c67f5dc5 100644 > --- a/drivers/usb/host/xhci-mtk.c > +++ b/drivers/usb/host/xhci-mtk.c > @@ -593,11 +593,11 @@ static int xhci_mtk_remove(struct platform_device *dev) > struct usb_hcd *shared_hcd = xhci->shared_hcd; > > usb_remove_hcd(shared_hcd); > - xhci->shared_hcd = NULL; > device_init_wakeup(&dev->dev, false); > > usb_remove_hcd(hcd); > usb_put_hcd(shared_hcd); > + xhci->shared_hcd = NULL; I may be wrong, but I have some concerns that this replaces the NULL pointer access with a UAF. Guenter > usb_put_hcd(hcd); > xhci_mtk_sch_exit(mtk); > xhci_mtk_clks_disable(mtk); > -- > 2.18.0
