arm64: add missing PAGE_ALIGN() to __dma_free()

commit 2cff98b9 upstream.

__dma_alloc() does a PAGE_ALIGN() on the passed in size argument before
doing anything else. __dma_free() does not. And because it doesn't, it is
possible to leak memory should size not be an integer multiple of PAGE_SIZE.

The solution is to add a PAGE_ALIGN() to __dma_free() like is done in
__dma_alloc().

Additionally, this patch removes a redundant PAGE_ALIGN() from
__dma_alloc_coherent(), since __dma_alloc_coherent() can only be called
from __dma_alloc(), which already does a PAGE_ALIGN() before the call.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dean Nelson <dnelson@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[ luis: backported to 3.16: based on Dean's 3.19 backport ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/arm64/mm/dma-mapping.c

@@ -86,7 +86,7 @@ static void __dma_free_coherent(struct device *dev, size_t size,
 
 		dma_release_from_contiguous(dev,
 					phys_to_page(paddr),
-					size >> PAGE_SHIFT);
+					PAGE_ALIGN(size) >> PAGE_SHIFT);
 	} else {
 		swiotlb_free_coherent(dev, size, vaddr, dma_handle);
 	}
@@ -138,6 +138,8 @@ static void __dma_free_noncoherent(struct device *dev, size_t size,
 {
 	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
 
+	size = PAGE_ALIGN(size);
+
 	vunmap(vaddr);
 	__dma_free_coherent(dev, size, swiotlb_addr, dma_handle, attrs);
 }