[PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner

From: Miaoqian Lin <linmq006@gmail.com>
To: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Eric Auger <eric.auger@redhat.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Cc: linmq006@gmail.com
Subject: [PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner
Date: Fri, 30 Dec 2022 12:31:00 +0400	[thread overview]
Message-ID: <20221230083100.1489569-1-linmq006@gmail.com> (raw)

iommu_group_get() returns the group with the reference incremented.
Move iommu_group_get() after owner check to fix the refcount leak.

Fixes: 89395ccedbc1 ("iommu: Add device-centric DMA ownership interfaces")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 drivers/iommu/iommu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index de91dd88705b..3a7dd8b61fab 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3185,14 +3185,16 @@ EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner);
  */
 int iommu_device_claim_dma_owner(struct device *dev, void *owner)
 {
-	struct iommu_group *group = iommu_group_get(dev);
+	struct iommu_group *group = NULL;
 	int ret = 0;
 
-	if (!group)
-		return -ENODEV;
 	if (WARN_ON(!owner))
 		return -EINVAL;
 
+	group = iommu_group_get(dev);
+	if (!group)
+		return -ENODEV;
+
 	mutex_lock(&group->mutex);
 	if (group->owner_cnt) {
 		if (group->owner != owner) {
-- 
2.25.1

