ARM: dma-mapping: add missing range check in dma_mmap()

dma_mmap() function in IOMMU-based dma-mapping implementation lacked
a check for valid range of mmap parameters (offset and buffer size), what
might have caused access beyond the allocated buffer. This patch fixes
this issue.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CC: stable@vger.kernel.org  # v3.6+

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 3b11d23c6749faa3eb70f415ee6f77961797340e..564fa6aa30dadc62d63ab45023ad544761dfa462 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1439,12 +1439,17 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
        unsigned long uaddr = vma->vm_start;
        unsigned long usize = vma->vm_end - vma->vm_start;
        struct page **pages = __iommu_get_pages(cpu_addr, attrs);
+       unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+       unsigned long off = vma->vm_pgoff;
 
        vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
 
        if (!pages)
                return -ENXIO;
 
+       if (off >= nr_pages || (usize >> PAGE_SHIFT) > nr_pages - off)
+               return -ENXIO;
+
        do {
                int ret = vm_insert_page(vma, uaddr, *pages++);
                if (ret) {