ACK: [d/azure][PATCH 1/2] PCI: hv: Fix a use-after-free bug in hv_eject_device_work()

[Sultan Alsawaf]

On Thu, Aug 08, 2019 at 12:34:52PM -0300, Marcelo Henrique Cerri wrote:
> From: Dexuan Cui <decui at microsoft.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1837661
> 
> Fix a use-after-free in hv_eject_device_work().
> 
> Fixes: 05f151a73ec2 ("PCI: hv: Fix a memory leak in hv_eject_device_work()")
> Signed-off-by: Dexuan Cui <decui at microsoft.com>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Reviewed-by: Michael Kelley <mikelley at microsoft.com>
> Cc: stable at vger.kernel.org
> (cherry picked from commit 4df591b20b80cb77920953812d894db259d85bd7)
> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
> ---
>  drivers/pci/controller/pci-hyperv.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 42af7f6a7c4c..ae91e708796f 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1888,6 +1888,7 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
>  static void hv_eject_device_work(struct work_struct *work)
>  {
>  	struct pci_eject_response *ejct_pkt;
> +	struct hv_pcibus_device *hbus;
>  	struct hv_pci_dev *hpdev;
>  	struct pci_dev *pdev;
>  	unsigned long flags;
> @@ -1898,6 +1899,7 @@ static void hv_eject_device_work(struct work_struct *work)
>  	} ctxt;
>  
>  	hpdev = container_of(work, struct hv_pci_dev, wrk);
> +	hbus = hpdev->hbus;
>  
>  	WARN_ON(hpdev->state != hv_pcichild_ejecting);
>  
> @@ -1908,8 +1910,7 @@ static void hv_eject_device_work(struct work_struct *work)
>  	 * because hbus->pci_bus may not exist yet.
>  	 */
>  	wslot = wslot_to_devfn(hpdev->desc.win_slot.slot);
> -	pdev = pci_get_domain_bus_and_slot(hpdev->hbus->sysdata.domain, 0,
> -					   wslot);
> +	pdev = pci_get_domain_bus_and_slot(hbus->sysdata.domain, 0, wslot);
>  	if (pdev) {
>  		pci_lock_rescan_remove();
>  		pci_stop_and_remove_bus_device(pdev);
> @@ -1917,9 +1918,9 @@ static void hv_eject_device_work(struct work_struct *work)
>  		pci_unlock_rescan_remove();
>  	}
>  
> -	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
> +	spin_lock_irqsave(&hbus->device_list_lock, flags);
>  	list_del(&hpdev->list_entry);
> -	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
> +	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
>  
>  	if (hpdev->pci_slot)
>  		pci_destroy_slot(hpdev->pci_slot);
> @@ -1928,7 +1929,7 @@ static void hv_eject_device_work(struct work_struct *work)
>  	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
>  	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
>  	ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot;
> -	vmbus_sendpacket(hpdev->hbus->hdev->channel, ejct_pkt,
> +	vmbus_sendpacket(hbus->hdev->channel, ejct_pkt,
>  			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
>  			 VM_PKT_DATA_INBAND, 0);
>  
> @@ -1937,7 +1938,9 @@ static void hv_eject_device_work(struct work_struct *work)
>  	/* For the two refs got in new_pcichild_device() */
>  	put_pcichild(hpdev);
>  	put_pcichild(hpdev);
> -	put_hvpcibus(hpdev->hbus);
> +	/* hpdev has been freed. Do not use it any more. */
> +
> +	put_hvpcibus(hbus);
>  }
>  
>  /**
> -- 
> 2.20.1
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

Acked-by: Sultan Alsawaf <sultan.alsawaf at canonical.com>