[PATCH] iommu/dma: fix for dereferencing before null checking

[Yunsheng Lin]

The cookie is dereferenced before null checking in the function
iommu_dma_init_domain.

This patch moves the dereferencing after the null checking.

Fixes: fdbe574eb693 ("iommu/dma: Allow MSI-only cookies")
Signed-off-by: Yunsheng Lin <linyunsh...@huawei.com>
---
 drivers/iommu/dma-iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index d991d40..cdf7814 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -303,13 +303,15 @@ static int iommu_dma_init_domain(struct iommu_domain 
*domain, dma_addr_t base,
                u64 size, struct device *dev)
 {
        struct iommu_dma_cookie *cookie = domain->iova_cookie;
-       struct iova_domain *iovad = &cookie->iovad;
        unsigned long order, base_pfn;
+       struct iova_domain *iovad;
        int attr;
 
        if (!cookie || cookie->type != IOMMU_DMA_IOVA_COOKIE)
                return -EINVAL;
 
+       iovad = &cookie->iovad;
+
        /* Use the smallest supported page size for IOVA granularity */
        order = __ffs(domain->pgsize_bitmap);
        base_pfn = max_t(unsigned long, 1, base >> order);
-- 
2.8.1