From mboxrd@z Thu Jan 1 00:00:00 1970 From: yuehaibing@huawei.com (YueHaibing) Date: Sat, 15 Sep 2018 19:29:20 +0800 Subject: [PATCH v2] ARM: dma-mapping: always clear allocated buffers In-Reply-To: <20180725070706.19576-1-yuehaibing@huawei.com> References: <20180725070706.19576-1-yuehaibing@huawei.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Ping. On 2018/7/25 15:07, YueHaibing wrote: > 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; >