From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
commit 44a182b9d17765514fa2b1cc911e4e65134eef93 upstream.
KASAN found a use-after-free in xhci_free_virt_device+0x33b/0x38e
where xhci_free_virt_device() sets slot id to 0 if udev exists:
if (dev->udev && dev->udev->slot_id)
dev->udev->slot_id = 0;
dev->udev will be true even if udev is freed because dev->udev is
not set to NULL.
set dev->udev pointer to NULL in xhci_free_dev()
The original patch went to stable so this fix needs to be applied
there as well.
Fixes: a400efe455f7 ("xhci: zero usb device slot_id member when disabling and freeing a xhci slot")
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
The original fix has been integrated into some recent -stable versions,
but wasn't backported to older LTS kernel like v4.9 or v4.4. The context
in xhci_free_dev() changed a bit because upstream added
xhci_disable_slot().
drivers/usb/host/xhci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index c190fabd1875..e9f5f9c32b49 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3656,6 +3656,9 @@ void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
}
spin_lock_irqsave(&xhci->lock, flags);
+
+ virt_dev->udev = NULL;
+
/* Don't disable the slot if the host controller is dead. */
state = readl(&xhci->op_regs->status);
if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING) ||
--
2.19.0.397.gdd90340f6a-goog
