ARM: 8426/1: 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+
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 1a7815e5421b6b1d3ad774b28915b84b52726136..c0865867ef0ded0c5036c11edf7f0ca1a25828f6 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1407,12 +1407,17 @@ 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) {