ARM: dma-mapping: add more sanity checks in arm_dma_mmap()

Add some sanity checks and forbid mmaping of buffers into vma areas larger
than allocated dma buffer.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f906d5f4cbd8..a2881c98fb03 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -611,16 +611,22 @@ int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 {
         int ret = -ENXIO;
 #ifdef CONFIG_MMU
+        unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+        unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
         unsigned long pfn = dma_to_pfn(dev, dma_addr);
+        unsigned long off = vma->vm_pgoff;
+
         vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
 
         if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
                 return ret;
 
-        ret = remap_pfn_range(vma, vma->vm_start,
-                              pfn + vma->vm_pgoff,
-                              vma->vm_end - vma->vm_start,
-                              vma->vm_page_prot);
+        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);
+        }
 #endif  /* CONFIG_MMU */
 
         return ret;