linux-kernel - [PATCH 2/4] iommu/vt-d: Fix PCI device refcount leak in prq_event

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Message-Id: <20221201040127.1962750-3-baolu.lu@linux.intel.com>
Date:   Thu,  1 Dec 2022 12:01:25 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] iommu/vt-d: Fix PCI device refcount leak in prq_event_thread()

From: Yang Yingliang <yangyingliang@...wei.com>

As comment of pci_get_domain_bus_and_slot() says, it returns a pci device
with refcount increment, when finish using it, the caller must decrease
the reference count by calling pci_dev_put(). So call pci_dev_put() after
using the 'pdev' to avoid refcount leak.

Besides, if the 'pdev' is null or intel_svm_prq_report() returns error,
there is no need to trace this fault.

Fixes: 06f4b8d09dba ("iommu/vt-d: Remove unnecessary SVA data accesses in page fault path")
Suggested-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
Link: https://lore.kernel.org/r/20221119144028.2452731-1-yangyingliang@huawei.com
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/svm.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index fe615c53479c..03b25358946c 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -748,12 +748,16 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		 * If prq is to be handled outside iommu driver via receiver of
 		 * the fault notifiers, we skip the page response here.
 		 */
-		if (!pdev || intel_svm_prq_report(iommu, &pdev->dev, req))
-			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
+		if (!pdev)
+			goto bad_req;
 
-		trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,
-				 req->priv_data[0], req->priv_data[1],
-				 iommu->prq_seq_number++);
+		if (intel_svm_prq_report(iommu, &pdev->dev, req))
+			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
+		else
+			trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,
+					 req->priv_data[0], req->priv_data[1],
+					 iommu->prq_seq_number++);
+		pci_dev_put(pdev);
 prq_advance:
 		head = (head + sizeof(*req)) & PRQ_RING_MASK;
 	}
-- 
2.34.1