[PATCH 02/26] arm64/iommu: improve mmap bounds checking

[Christoph Hellwig]

The nr_pages checks should be done for all mmap requests, not just those
using remap_pfn_range.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 arch/arm64/mm/dma-mapping.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 674860e3e478..604c638b2787 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -73,19 +73,9 @@ static int __swiotlb_get_sgtable_page(struct sg_table *sgt,
 static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
                              unsigned long pfn, size_t size)
 {
-       int ret = -ENXIO;
-       unsigned long nr_vma_pages = vma_pages(vma);
-       unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
-       unsigned long off = vma->vm_pgoff;
-
-       if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
-               ret = remap_pfn_range(vma, vma->vm_start,
-                                     pfn + off,
-                                     vma->vm_end - vma->vm_start,
-                                     vma->vm_page_prot);
-       }
-
-       return ret;
+       return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
+                             vma->vm_end - vma->vm_start,
+                             vma->vm_page_prot);
 }
 #endif /* CONFIG_IOMMU_DMA */
 
@@ -241,6 +231,8 @@ static int __iommu_mmap_attrs(struct device *dev, struct 
vm_area_struct *vma,
                              void *cpu_addr, dma_addr_t dma_addr, size_t size,
                              unsigned long attrs)
 {
+       unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+       unsigned long off = vma->vm_pgoff;
        struct vm_struct *area;
        int ret;
 
@@ -249,6 +241,9 @@ static int __iommu_mmap_attrs(struct device *dev, struct 
vm_area_struct *vma,
        if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
                return ret;
 
+       if (off >= nr_pages || vma_pages(vma) > nr_pages - off)
+               return -ENXIO;
+
        if (!is_vmalloc_addr(cpu_addr)) {
                unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
                return __swiotlb_mmap_pfn(vma, pfn, size);
-- 
2.20.1

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