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arm64: dma-mapping: always clear allocated buffers

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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>
This commit is contained in:
Marek Szyprowski 2015-04-23 12:46:16 +01:00 committed by Will Deacon
parent 6544e67bfb
commit 6829e274a6
1 changed files with 2 additions and 4 deletions
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6
arch/arm64/mm/dma-mapping.c
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@ -67,8 +67,7 @@ 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);
memset(ptr, 0, size);
}
return ptr;
@ -113,8 +112,7 @@ 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);
memset(addr, 0, size);
return addr;
} else {
return swiotlb_alloc_coherent(dev, size, dma_handle, flags);