4.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marek Szyprowski <m.szyprow...@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.szyprow...@samsung.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@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);
--
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