iommu/dma: Account for min_align_mask w/swiotlb

commit 2cbc61a1b1665c84282dbf2b1747ffa0b6248639 upstream.

Pass the non-aligned size to __iommu_dma_map when using swiotlb bounce
buffers in iommu_dma_map_page, to account for min_align_mask.

To deal with granule alignment, __iommu_dma_map maps iova_align(size +
iova_off) bytes starting at phys - iova_off. If iommu_dma_map_page
passes aligned size when using swiotlb, then this becomes
iova_align(iova_align(orig_size) + iova_off). Normally iova_off will be
zero when using swiotlb. However, this is not the case for devices that
set min_align_mask. When iova_off is non-zero, __iommu_dma_map ends up
mapping an extra page at the end of the buffer. Beyond just being a
security issue, the extra page is not cleaned up by __iommu_dma_unmap.
This causes problems when the IOVA is reused, due to collisions in the
iommu driver.  Just passing the original size is sufficient, since
__iommu_dma_map will take care of granule alignment.

Fixes: 1f221a0d0dbf ("swiotlb: respect min_align_mask")
Signed-off-by: David Stevens <stevensd@chromium.org>
Link: https://lore.kernel.org/r/20210929023300.335969-8-stevensd@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 26f754b..276b6fc 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -806,7 +806,6 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
        struct iommu_domain *domain = iommu_get_dma_domain(dev);
        struct iommu_dma_cookie *cookie = domain->iova_cookie;
        struct iova_domain *iovad = &cookie->iovad;
-       size_t aligned_size = size;
        dma_addr_t iova, dma_mask = dma_get_mask(dev);
 
        /*
@@ -815,7 +814,7 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
         */
        if (dev_use_swiotlb(dev) && iova_offset(iovad, phys | size)) {
                void *padding_start;
-               size_t padding_size;
+               size_t padding_size, aligned_size;
 
                aligned_size = iova_align(iovad, size);
                phys = swiotlb_tbl_map_single(dev, phys, size, aligned_size,
@@ -840,7 +839,7 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
        if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                arch_sync_dma_for_device(phys, size, dir);
 
-       iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
+       iova = __iommu_dma_map(dev, phys, size, prot, dma_mask);
        if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(dev, phys))
                swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
        return iova;