From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D1F2C6778F for ; Wed, 25 Jul 2018 07:07:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE54620882 for ; Wed, 25 Jul 2018 07:07:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE54620882 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728593AbeGYIRo (ORCPT ); Wed, 25 Jul 2018 04:17:44 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:33585 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728461AbeGYIRo (ORCPT ); Wed, 25 Jul 2018 04:17:44 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 3E4B61675883F; Wed, 25 Jul 2018 15:07:21 +0800 (CST) Received: from localhost (10.177.31.96) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.382.0; Wed, 25 Jul 2018 15:07:12 +0800 From: YueHaibing To: , , CC: , , , , , , , , , YueHaibing Subject: [PATCH v2] ARM: dma-mapping: always clear allocated buffers Date: Wed, 25 Jul 2018 15:07:06 +0800 Message-ID: <20180725070706.19576-1-yuehaibing@huawei.com> X-Mailer: git-send-email 2.10.2.windows.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.31.96] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Wang reported dma_zalloc_coherent doesn't work as expect on his armv7,the allocated mem is not zeroed.The reason is __alloc_from_pool doesn't honor __GFP_ZERO. As commit 6829e274a623 ("arm64: dma-mapping: always clear allocated buffers") has pointed out,buffers allocated by dma_alloc_coherent() are always zeroed on most architectures. 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 ARM architecture with other implementations by unconditionally zeroing allocated buffer.Also to fix dma_zalloc_coherent behavior. Reported-by: Sean Wang Signed-off-by: YueHaibing Reviewed-by: zhong jiang --- v2: reference more argument from arm64 commit as Christoph suggested --- arch/arm/mm/dma-mapping.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 6656647..cf5882f 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -564,6 +564,7 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page) *ret_page = phys_to_page(phys); ptr = (void *)val; + memset(ptr, 0, size); } return ptr; -- 2.7.0