From: Matt Evans <matt@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index e8ab189..5c0ae90 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
--
1.7.1
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