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Subject[PATCH 02/21] arm64/iommu: improve mmap bounds checking
Date
The nr_pages checks should be done for all mmap requests, not just those
using remap_pfn_range.

Signed-off-by: Christoph Hellwig <hch@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 be88beb2e377..e54288921e72 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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