From a2ff864b53eac9a0e9b05bfe9d1781ccd6c2af71 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 14 Apr 2014 13:48:47 -0400 Subject: [PATCH] USB: fix crash during hotplug of PCI USB controller card The code in hcd-pci.c that matches up EHCI controllers with their companion UHCI or OHCI controllers assumes that the private drvdata fields don't get set too early. However, it turns out that this field gets set by usb_create_hcd(), before hcd-pci expects it, and this can result in a crash when two controllers are probed in parallel (as can happen when a new controller card is hotplugged). The companions_rwsem lock was supposed to prevent this sort of thing, but usb_create_hcd() is called outside the scope of the rwsem. A simple solution is to check that the root-hub pointer has been initialized as well as the drvdata field. This doesn't happen until usb_add_hcd() is called; that call and the check are both protected by the rwsem. This patch should be applied to stable kernels from 3.10 onward. Signed-off-by: Alan Stern Reported-by: Stefani Seibold Tested-by: Stefani Seibold CC: Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hcd-pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c index d59d993..1f02e65 100644 --- a/drivers/usb/core/hcd-pci.c +++ b/drivers/usb/core/hcd-pci.c @@ -75,7 +75,7 @@ static void for_each_companion(struct pci_dev *pdev, struct usb_hcd *hcd, PCI_SLOT(companion->devfn) != slot) continue; companion_hcd = pci_get_drvdata(companion); - if (!companion_hcd) + if (!companion_hcd || !companion_hcd->self.root_hub) continue; fn(pdev, hcd, companion, companion_hcd); } -- 2.7.4