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SubjectRe: [PATCH v3 6/9] iommu/dma-iommu.c: Convert to use vm_insert_range
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On 06/12/2018 18:43, Souptick Joarder wrote:
> Convert to use vm_insert_range() to map range of kernel
> memory to user vma.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Matthew Wilcox <willy@infradead.org>
> ---
> drivers/iommu/dma-iommu.c | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index d1b0475..a2c65e2 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -622,17 +622,10 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
>
> int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
> {
> - unsigned long uaddr = vma->vm_start;
> - unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> - int ret = -ENXIO;
> + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>
> - for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
> - ret = vm_insert_page(vma, uaddr, pages[i]);
> - if (ret)
> - break;
> - uaddr += PAGE_SIZE;
> - }
> - return ret;
> + return vm_insert_range(vma, vma->vm_start,
> + pages + vma->vm_pgoff, count);

You also need to adjust count to compensate for the pages skipped by
vm_pgoff, otherwise you've got an out-of-bounds dereference triggered
from userspace, which is pretty high up the "not good" scale (not to
mention the entire call would then propagate -EFAULT back from
vm_insert_page() and thus always appear to fail for nonzero offsets).

Robin.

> }
>
> static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
>

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