Messages in this thread Patch in this message | | | Subject | Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking | From | Robin Murphy <> | Date | Fri, 5 Apr 2019 18:30:52 +0100 |
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On 27/03/2019 08:04, Christoph Hellwig wrote: > The nr_pages checks should be done for all mmap requests, not just those > using remap_pfn_range.
Hmm, the logic in iommu_dma_mmap() inherently returns an error for the "off >= nr_pages" case already. It's also supposed to be robust against the "vma_pages(vma) > nr_pages - off" condition, although by making the partial mapping and treating it as a success, rather than doing nothing and returning an error. What's the exact motivation here?
Robin.
> 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); >
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