From c210f9f994df51515fe0c956d13e3f2b63cf9fe2 Mon Sep 17 00:00:00 2001
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Thu, 23 Apr 2015 12:46:16 +0100
Subject: [PATCH] arm64: dma-mapping: always clear allocated buffers
[ Upstream commit 6829e274a623187c24f7cfc0e3d35f25d087fcc5 ]
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.
Bug: 29795245
CRs-Fixed: 1041735
Change-Id: I74bf024e0f603ca8c0b05430dc2ee154d579cfb2
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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Git-commit: a142e9641dcbead2c8845c949ad518acac96ed28
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[lmark@codeaurora.org: resolve merge conflicts]
Signed-off-by: Liam Mark <lmark@codeaurora.org>
---
arch/arm/mm/dma-mapping.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 1363ed306663..ba9aacb74185 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -558,6 +558,7 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page)
if (pageno < pool->nr_pages) {
bitmap_set(pool->bitmap, pageno, count);
ptr = pool->vaddr + PAGE_SIZE * pageno;
+ memset(ptr, 0, size);
*ret_page = pool->pages[pageno];
} else {
pr_err_once("ERROR: %u KiB atomic DMA coherent pool is too small!\n"
--
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