| Message ID | 20180612110840.30436-1-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Marek, On Tue, Jun 12, 2018 at 01:08:40PM +0200, Marek Szyprowski wrote: > dma_alloc_*() buffers might be exposed to userspace via mmap() call, so > they should be cleared on allocation. In case of IOMMU-based dma-mapping > implementation such buffer clearing was missing in the code path for > DMA_ATTR_FORCE_CONTIGUOUS flag handling, because dma_alloc_from_contiguous() > doesn't honor __GFP_ZERO flag. This patch fixes this issue. For more > information on clearing buffers allocated by dma_alloc_* functions, > see commit 6829e274a623 ("arm64: dma-mapping: always clear allocated > buffers"). > > Fixes: 44176bb38fa4 ("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU") > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> I'll queue this patch for -rc2 but I hope a proper fix goes into the CMA code. Thanks.
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 632d32109755..aa0037a3185f 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -629,13 +629,14 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, size >> PAGE_SHIFT); return NULL; } - if (!coherent) - __dma_flush_area(page_to_virt(page), iosize); - addr = dma_common_contiguous_remap(page, size, VM_USERMAP, prot, __builtin_return_address(0)); - if (!addr) { + if (addr) { + memset(addr, 0, size); + if (!coherent) + __dma_flush_area(page_to_virt(page), iosize); + } else { iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs); dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
dma_alloc_*() buffers might be exposed to userspace via mmap() call, so they should be cleared on allocation. In case of IOMMU-based dma-mapping implementation such buffer clearing was missing in the code path for DMA_ATTR_FORCE_CONTIGUOUS flag handling, because dma_alloc_from_contiguous() doesn't honor __GFP_ZERO flag. This patch fixes this issue. For more information on clearing buffers allocated by dma_alloc_* functions, see commit 6829e274a623 ("arm64: dma-mapping: always clear allocated buffers"). Fixes: 44176bb38fa4 ("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU") Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- v2: - fixed incorrect commit id in commit body (thanks to Geert) - extended description with information that dma_alloc_from_contiguous() lacks __GFP_ZERO support --- arch/arm64/mm/dma-mapping.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)