diff mbox

[v2,1/2] vfio iommu type1: Fix size argument to vfio_find_dma() during DMA UNMAP.

Message ID 1481048814-29752-1-git-send-email-kwankhede@nvidia.com
State New
Headers show

Commit Message

Kirti Wankhede Dec. 6, 2016, 6:26 p.m. UTC 
Passing zero for the size to vfio_find_dma() isn't compatible with
matching the start address of an existing vfio_dma. Doing so triggers a
corner case. In vfio_find_dma(), when the start address is equal to
dma->iova and size is 0, check for the end of search range makes it to
take wrong side of RB-tree. That fails the search even though the address
is present in mapped dma ranges. Due to this, in vfio_dma_do_unmap(),
while checking boundary conditions, size should be set to 1 for verifying
start address of unmap range.
vfio_find_dma() is also used to verify last address in unmap range with
size = 0, but in that case address to be searched is calculated with
size - 1 and so it works correctly.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Neo Jia <cjia@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Alex Williamson Dec. 6, 2016, 7:34 p.m. UTC | #1 
On Tue, 6 Dec 2016 23:56:54 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> Passing zero for the size to vfio_find_dma() isn't compatible with
> matching the start address of an existing vfio_dma. Doing so triggers a
> corner case. In vfio_find_dma(), when the start address is equal to
> dma->iova and size is 0, check for the end of search range makes it to
> take wrong side of RB-tree. That fails the search even though the address
> is present in mapped dma ranges. Due to this, in vfio_dma_do_unmap(),
> while checking boundary conditions, size should be set to 1 for verifying
> start address of unmap range.
> vfio_find_dma() is also used to verify last address in unmap range with
> size = 0, but in that case address to be searched is calculated with
> size - 1 and so it works correctly.

I think this last sentence should actually read "start + size - 1", or
at least that makes it more understandable for me.  I'll make that
change and apply these. Thanks,

Alex

> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Signed-off-by: Neo Jia <cjia@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index a28fbddb505c..8e9e94ccb2ff 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -826,7 +826,7 @@ again:
>  	 * mappings within the range.
>  	 */
>  	if (iommu->v2) {
> -		dma = vfio_find_dma(iommu, unmap->iova, 0);
> +		dma = vfio_find_dma(iommu, unmap->iova, 1);
>  		if (dma && dma->iova != unmap->iova) {
>  			ret = -EINVAL;
>  			goto unlock;
diff mbox

Patch

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index a28fbddb505c..8e9e94ccb2ff 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -826,7 +826,7 @@  again:
 	 * mappings within the range.
 	 */
 	if (iommu->v2) {
-		dma = vfio_find_dma(iommu, unmap->iova, 0);
+		dma = vfio_find_dma(iommu, unmap->iova, 1);
 		if (dma && dma->iova != unmap->iova) {
 			ret = -EINVAL;
 			goto unlock;