vfio iommu type1: Fix size argument to vfio_find_dma() during DMA UNMAP.

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
start + size - 1 and so it works correctly.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Neo Jia <cjia@nvidia.com>
[aw: changelog tweak]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 7274fe27ccac94a5d50f2d64d122774c164314f5..198cf398427e07d7e11734977223b55b380fce4f 100644 (file)
--- 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;