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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Breno Leitao <leitao@debian.org>,
	linuxppc-dev@lists.ozlabs.org, Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.14 010/109] powerpc/iommu: Avoid derefence before pointer check
Date: Sat,  9 Nov 2019 21:44:02 -0500	[thread overview]
Message-ID: <20191110024541.31567-10-sashal@kernel.org> (raw)
In-Reply-To: <20191110024541.31567-1-sashal@kernel.org>

From: Breno Leitao <leitao@debian.org>

[ Upstream commit 984ecdd68de0fa1f63ce205d6c19ef5a7bc67b40 ]

The tbl pointer is being derefenced by IOMMU_PAGE_SIZE prior the check
if it is not NULL.

Just moving the dereference code to after the check, where there will
be guarantee that 'tbl' will not be NULL.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/kernel/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index af7a20dc6e093..80b6caaa9b92e 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -785,9 +785,9 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
 
 	vaddr = page_address(page) + offset;
 	uaddr = (unsigned long)vaddr;
-	npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE(tbl));
 
 	if (tbl) {
+		npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE(tbl));
 		align = 0;
 		if (tbl->it_page_shift < PAGE_SHIFT && size >= PAGE_SIZE &&
 		    ((unsigned long)vaddr & ~PAGE_MASK) == 0)
-- 
2.20.1


       reply	other threads:[~2019-11-10  3:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191110024541.31567-1-sashal@kernel.org>
2019-11-10  2:44 ` Sasha Levin [this message]
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 011/109] powerpc/64s/hash: Fix stab_rr off by one initialization Sasha Levin
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 012/109] powerpc/pseries: Disable CPU hotplug across migrations Sasha Levin
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 013/109] powerpc: Fix duplicate const clang warning in user access code Sasha Levin
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 016/109] libfdt: Ensure INT_MAX is defined in libfdt_env.h Sasha Levin
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 019/109] net: toshiba: fix return type of ndo_start_xmit function Sasha Levin
2019-11-10  2:44 ` [PATCH AUTOSEL 4.14 045/109] net: freescale: " Sasha Levin

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