On Tue, Dec 18, 2018 at 01:52:09AM +0530, Souptick Joarder wrote: > Convert to use vm_insert_range() to map range of kernel > memory to user vma. > > Signed-off-by: Souptick Joarder <[email protected]> > --- > arch/arm/mm/dma-mapping.c | 21 +++++++-------------- > 1 file changed, 7 insertions(+), 14 deletions(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 661fe48..7cbcde5 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1582,31 +1582,24 @@ static int __arm_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 uaddr = vma->vm_start; > - unsigned long usize = vma->vm_end - vma->vm_start; > + unsigned long page_count = vma_pages(vma); > struct page **pages = __iommu_get_pages(cpu_addr, attrs); > unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; > unsigned long off = vma->vm_pgoff; > + int err; > > if (!pages) > return -ENXIO; > > - if (off >= nr_pages || (usize >> PAGE_SHIFT) > nr_pages - off) > + if (off >= nr_pages) > return -ENXIO;
Are you sure you can make this change? You are restricting the offset to be within 0..nr_pages which ensures that the initial struct page that is passed to vm_insert_range() is valid, but I think the removal of the following check is unsafe. Your new vm_insert_range() function only checks page_count <= vma_pages(vma), which it will be since it _is_ vma_pages(vma). With the removal of the second condition, there will be nothing checking that (eg) off may be nr_pages - 1, and page_count=50, meaning that vm_insert_range() will walk off the end of the page array. Please take another look at this. What about the other callsites of your new function - do they have the same issue? -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
