Commit 6829e274 authored Apr 23, 2015 by Marek Szyprowski Committed by Will Deacon Apr 27, 2015

arm64: dma-mapping: always clear allocated buffers



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.

Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 6544e67b

arch/arm64/mm/dma-mapping.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -67,7 +67,6 @@ 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);
		}

		@@ -113,7 +112,6 @@ 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);
		return addr;
		} else {