| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.0 39/72] arm64: dma-mapping: always clear allocated buffers | Date | Mon, 11 May 2015 10:54:45 -0700 |
| |
4.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marek Szyprowski <m.szyprowski@samsung.com>
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@samsung.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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);
|