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Groups > linux.kernel > #1345270

[PATCH v2 for-4.5] vfio: fix ioctl error handling

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Calling return copy_to_user(...) in an ioctl will not
do the right thing if there's a pagefault:
copy_to_user returns the number of bytes not copied
in this case.

Fix up vfio to do
	if (copy_to_user(...))
		return -EFAULT;
	return 0;

everywhere.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Changes from v1:
	fix up good path logic to return 0.

Compiled only.

 drivers/vfio/pci/vfio_pci.c                  | 12 +++++++++---
 drivers/vfio/platform/vfio_platform_common.c | 12 +++++++++---
 drivers/vfio/vfio_iommu_type1.c              |  8 ++++++--
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 2760a7b..286b91f 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -446,7 +446,9 @@ static long vfio_pci_ioctl(void *device_data,
 		info.num_regions = VFIO_PCI_NUM_REGIONS;
 		info.num_irqs = VFIO_PCI_NUM_IRQS;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
 		struct pci_dev *pdev = vdev->pdev;
@@ -520,7 +522,9 @@ static long vfio_pci_ioctl(void *device_data,
 			return -EINVAL;
 		}
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
 		struct vfio_irq_info info;
@@ -555,7 +559,9 @@ static long vfio_pci_ioctl(void *device_data,
 		else
 			info.flags |= VFIO_IRQ_INFO_NORESIZE;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_SET_IRQS) {
 		struct vfio_irq_set hdr;
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 418cdd9..0fc6b75 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -219,7 +219,9 @@ static long vfio_platform_ioctl(void *device_data,
 		info.num_regions = vdev->num_regions;
 		info.num_irqs = vdev->num_irqs;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
 		struct vfio_region_info info;
@@ -240,7 +242,9 @@ static long vfio_platform_ioctl(void *device_data,
 		info.size = vdev->regions[info.index].size;
 		info.flags = vdev->regions[info.index].flags;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
 		struct vfio_irq_info info;
@@ -259,7 +263,9 @@ static long vfio_platform_ioctl(void *device_data,
 		info.flags = vdev->irqs[info.index].flags;
 		info.count = vdev->irqs[info.index].count;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_DEVICE_SET_IRQS) {
 		struct vfio_irq_set hdr;
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 6f1ea3d..557dfc6 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -999,7 +999,9 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 
 		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
 
 	} else if (cmd == VFIO_IOMMU_MAP_DMA) {
 		struct vfio_iommu_type1_dma_map map;
@@ -1032,7 +1034,9 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 		if (ret)
 			return ret;
 
-		return copy_to_user((void __user *)arg, &unmap, minsz);
+		if (copy_to_user((void __user *)arg, &unmap, minsz))
+			return -EFAULT;
+		return 0;
 	}
 
 	return -ENOTTY;
-- 
MST

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[PATCH v2 for-4.5] vfio: fix ioctl error handling "Michael S. Tsirkin" <mst@redhat.com> - 2016-02-28 15:00 +0100
  Re: [PATCH v2 for-4.5] vfio: fix ioctl error handling "Michael S. Tsirkin" <mst@redhat.com> - 2016-02-28 15:30 +0100
    Re: [PATCH v2 for-4.5] vfio: fix ioctl error handling Alex Williamson <alex.williamson@redhat.com> - 2016-02-28 15:40 +0100
      Re: [PATCH v2 for-4.5] vfio: fix ioctl error handling "Michael S. Tsirkin" <mst@redhat.com> - 2016-02-28 16:00 +0100
  Re: [PATCH v2 for-4.5] vfio: fix ioctl error handling Alex Williamson <alex.williamson@redhat.com> - 2016-02-28 15:30 +0100

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