xhci: Fix null pointer dereference when host dies

Make sure xhci_free_dev() and xhci_kill_endpoint_urbs() do not race
and cause null pointer dereference when host suddenly dies.

Usb core may call xhci_free_dev() which frees the xhci->devs[slot_id]
virt device at the same time that xhci_kill_endpoint_urbs() tries to
loop through all the device's endpoints, checking if there are any
cancelled urbs left to give back.

hold the xhci spinlock while freeing the virt device

Cc: stable@vger.kernel.org
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230116142216.1141605-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 79d7931..50b4121 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3974,6 +3974,7 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_virt_device *virt_dev;
        struct xhci_slot_ctx *slot_ctx;
+       unsigned long flags;
        int i, ret;
 
        /*
@@ -4000,7 +4001,11 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
                virt_dev->eps[i].ep_state &= ~EP_STOP_CMD_PENDING;
        virt_dev->udev = NULL;
        xhci_disable_slot(xhci, udev->slot_id);
+
+       spin_lock_irqsave(&xhci->lock, flags);
        xhci_free_virt_device(xhci, udev->slot_id);
+       spin_unlock_irqrestore(&xhci->lock, flags);
+
 }
 
 int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)