Return-Path: Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:45273 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752929AbbEKKxs (ORCPT ); Mon, 11 May 2015 06:53:48 -0400 From: Will Deacon To: stable@vger.kernel.org Cc: gregkh@linuxfoundation.org, Marek Szyprowski , Will Deacon Subject: [PATCH] arm64: dma-mapping: always clear allocated buffers Date: Mon, 11 May 2015 11:53:40 +0100 Message-Id: <1431341620-4968-1-git-send-email-will.deacon@arm.com> Sender: stable-owner@vger.kernel.org List-ID: From: Marek Szyprowski [Stable backport of 6829e274a623 to 3.14.y] Buffers allocated by dma_alloc_coherent() are always zeroed on Alpha, ARM (32bit), MIPS, PowerPC, x86/x86_64 and probably other architectures. It turned out that some drivers rely on this 'feature'. Allocated buffer might be also exposed to userspace with dma_mmap() call, so clearing it is desired from security point of view to avoid exposing random memory to userspace. This patch unifies dma_alloc_coherent() behavior on ARM64 architecture with other implementations by unconditionally zeroing allocated buffer. Cc: # v3.14 only Signed-off-by: Marek Szyprowski [will: ported to 3.14.y] Signed-off-by: Will Deacon --- arch/arm64/mm/dma-mapping.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 3974881388bb..b76159a153a5 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -54,8 +54,7 @@ static void *arm64_swiotlb_alloc_coherent(struct device *dev, size_t size, *dma_handle = phys_to_dma(dev, page_to_phys(page)); addr = page_address(page); - if (flags & __GFP_ZERO) - memset(addr, 0, size); + memset(addr, 0, size); return addr; } else { return swiotlb_alloc_coherent(dev, size, dma_handle, flags); -- 2.1.4