This is a note to let you know that I've just added the patch titled arm64: dma-mapping: always clear allocated buffers to the 4.0-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-dma-mapping-always-clear-allocated-buffers.patch and it can be found in the queue-4.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6829e274a623187c24f7cfc0e3d35f25d087fcc5 Mon Sep 17 00:00:00 2001 From: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Date: Thu, 23 Apr 2015 12:46:16 +0100 Subject: arm64: dma-mapping: always clear allocated buffers From: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> 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 <m.szyprowski@xxxxxxxxxxx> Signed-off-by: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/mm/dma-mapping.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- 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 si *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 *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); Patches currently in stable-queue which might be from m.szyprowski@xxxxxxxxxxx are queue-4.0/arm64-dma-mapping-always-clear-allocated-buffers.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html