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authorMathias Nyman <mathias.nyman@linux.intel.com>2018-05-14 11:57:23 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-11-27 16:08:02 +0100
commitd57a6bb22085ed9bebe300497da8cae1dcb4f266 (patch)
parent645cb3965b1d3f841c5318af0807588de4ae9c13 (diff)
xhci: Fix USB3 NULL pointer dereference at logical disconnect.
commit 2278446e2b7cd33ad894b32e7eb63afc7db6c86e upstream. Hub driver will try to disable a USB3 device twice at logical disconnect, racing with xhci_free_dev() callback from the first port disable. This can be triggered with "udisksctl power-off --block-device <disk>" or by writing "1" to the "remove" sysfs file for a USB3 device in 4.17-rc4. USB3 devices don't have a similar disabled link state as USB2 devices, and use a U3 suspended link state instead. In this state the port is still enabled and connected. hub_port_connect() first disconnects the device, then later it notices that device is still enabled (due to U3 states) it will try to disable the port again (set to U3). The xhci_free_dev() called during device disable is async, so checking for existing xhci->devs[i] when setting link state to U3 the second time was successful, even if device was being freed. The regression was caused by, and whole thing revealed by, Commit 44a182b9d177 ("xhci: Fix use-after-free in xhci_free_virt_device") which sets xhci->devs[i]->udev to NULL before xhci_virt_dev() returned. and causes a NULL pointer dereference the second time we try to set U3. Fix this by checking xhci->devs[i]->udev exists before setting link state. The original patch went to stable so this fix needs to be applied there as well. Fixes: 44a182b9d177 ("xhci: Fix use-after-free in xhci_free_virt_device") Cc: <stable@vger.kernel.org> Reported-by: Jordan Glover <Golden_Miller83@protonmail.ch> Tested-by: Jordan Glover <Golden_Miller83@protonmail.ch> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index f788f80fe1aa..aee29604bd79 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -348,7 +348,7 @@ int xhci_find_slot_id_by_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
slot_id = 0;
for (i = 0; i < MAX_HC_SLOTS; i++) {
- if (!xhci->devs[i])
+ if (!xhci->devs[i] || !xhci->devs[i]->udev)
speed = xhci->devs[i]->udev->speed;
if (((speed >= USB_SPEED_SUPER) == (hcd->speed >= HCD_USB3))