From 7ed603ecf8b68ab81f4c83097d3063d43ec73bb8 Mon Sep 17 00:00:00 2001 From: Matt Evans Date: Tue, 29 Mar 2011 13:40:56 +1100 Subject: [PATCH] xhci: Add an assertion to check for virt_dev=0 bug. During a "plug-unplug" stress test on an NEC xHCI card, a null pointer dereference was observed. xhci_address_device() dereferenced a null virt_dev (possibly an erroneous udev->slot_id?); this patch adds a WARN_ON & message to aid debug if it can be recreated. Signed-off-by: Matt Evans Signed-off-by: Sarah Sharp --- drivers/usb/host/xhci.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index e8ab1899c88..5c0ae90df31 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -2546,6 +2546,17 @@ int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev) virt_dev = xhci->devs[udev->slot_id]; + if (WARN_ON(!virt_dev)) { + /* + * In plug/unplug torture test with an NEC controller, + * a zero-dereference was observed once due to virt_dev = 0. + * Print useful debug rather than crash if it is observed again! + */ + xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n", + udev->slot_id); + return -EINVAL; + } + slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx); /* * If this is the first Set Address since device plug-in or -- 2.20.1