From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932778AbbEZQLn (ORCPT ); Tue, 26 May 2015 12:11:43 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33792 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932110AbbEZPmT (ORCPT ); Tue, 26 May 2015 11:42:19 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Marek Szyprowski , Will Deacon , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 10/92] arm64: dma-mapping: always clear allocated buffers Date: Tue, 26 May 2015 08:40:14 -0700 Message-Id: <1432654896-28478-11-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1432654896-28478-1-git-send-email-kamal@canonical.com> References: <1432654896-28478-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Marek Szyprowski commit 6829e274a623187c24f7cfc0e3d35f25d087fcc5 upstream. 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. Signed-off-by: Marek Szyprowski Signed-off-by: Will Deacon Signed-off-by: Kamal Mostafa --- arch/arm64/mm/dma-mapping.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index df34a70..6efbb52 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -67,8 +67,7 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags) *ret_page = phys_to_page(phys); ptr = (void *)val; - if (flags & __GFP_ZERO) - memset(ptr, 0, size); + memset(ptr, 0, size); } return ptr; @@ -113,8 +112,7 @@ static void *__dma_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); -- 1.9.1