USB: xhci: Fix bug memory free after failed initialization.

If the xHCI driver fails during the memory initialization, xhci->ir_set
may not be a valid pointer.  Check that it points to valid DMA'able memory
before writing to that address during the memory freeing process.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 1db4fea8c17..732580c6cbe 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -802,9 +802,11 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
         int i;
 
         /* Free the Event Ring Segment Table and the actual Event Ring */
-        xhci_writel(xhci, 0, &xhci->ir_set->erst_size);
-        xhci_write_64(xhci, 0, &xhci->ir_set->erst_base);
-        xhci_write_64(xhci, 0, &xhci->ir_set->erst_dequeue);
+        if (xhci->ir_set) {
+                xhci_writel(xhci, 0, &xhci->ir_set->erst_size);
+                xhci_write_64(xhci, 0, &xhci->ir_set->erst_base);
+                xhci_write_64(xhci, 0, &xhci->ir_set->erst_dequeue);
+        }
         size = sizeof(struct xhci_erst_entry)*(xhci->erst.num_entries);
         if (xhci->erst.entries)
                 pci_free_consistent(pdev, size,