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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 <matt@ozlabs.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
This commit is contained in:
Matt Evans 2011-03-29 13:40:56 +11:00 committed by Sarah Sharp
parent 92a3da410a
commit 7ed603ecf8
1 changed files with 11 additions and 0 deletions
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11
drivers/usb/host/xhci.c
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@ -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