Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add

From	Sinan Kaya <okaya@codeaurora.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add
Date	2017-04-14 03:20 +0200
Message-ID	<tvY42-2OS-9@gated-at.bofh.it> (permalink)
References	<ttQDD-FB-3@gated-at.bofh.it> <ttQDE-FB-13@gated-at.bofh.it> <tvTQK-8fn-27@gated-at.bofh.it> <tvUa6-b9-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 4/13/2017 5:02 PM, Bjorn Helgaas wrote:
> I do see that you change the deallocation in patch [5/5], but I think
> the deallocation change should be in the same patch as the allocation
> change.  Otherwise I think we have a use-after-free problem in this
> sequence:

Sure, I'll reorder. As you can see here, link will be only removed if
root port is being removed.

Without this, we'll hit the use after free issue you mentioned.

	if (pdev->has_secondary_link) {
		link = pdev->link_state;
		down_read(&pci_bus_sem);
		mutex_lock(&aspm_lock);

		list_del(&link->sibling);
		list_del(&link->link);

		/* Clock PM is for endpoint device */
		free_link_state(link);
		mutex_unlock(&aspm_lock);
		up_read(&pci_bus_sem);
		return;
	}  

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

Thread

Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add Bjorn Helgaas <helgaas@kernel.org> - 2017-04-13 22:50 +0200
  Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add Bjorn Helgaas <helgaas@kernel.org> - 2017-04-13 23:10 +0200
    Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add Sinan Kaya <okaya@codeaurora.org> - 2017-04-14 03:20 +0200
      Re: [PATCH V8 3/5] PCI/ASPM: add init hook to device_add Bjorn Helgaas <bhelgaas@google.com> - 2017-04-14 03:40 +0200

csiph-web