4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: Marek Szyprowski <[email protected]> [ Upstream commit dd65a941f6ba473a5cb9d013d57fa43b48450a04 ] 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 <[email protected]> Signed-off-by: Catalin Marinas <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/arm64/mm/dma-mapping.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -588,13 +588,14 @@ static void *__iommu_alloc_attrs(struct 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);
