linux-kernel - [PATCH 3/4] iommu/vt-d: Fix PCI device refcount leak in has_external

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Message-Id: <20221201040127.1962750-4-baolu.lu@linux.intel.com>
Date:   Thu,  1 Dec 2022 12:01:26 +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 3/4] iommu/vt-d: Fix PCI device refcount leak in has_external_pci()

From: Xiongfeng Wang <wangxiongfeng2@...wei.com>

for_each_pci_dev() is implemented by pci_get_device(). The comment of
pci_get_device() says that it will increase the reference count for the
returned pci_dev and also decrease the reference count for the input
pci_dev @from if it is not NULL.

If we break for_each_pci_dev() loop with pdev not NULL, we need to call
pci_dev_put() to decrease the reference count. Add the missing
pci_dev_put() before 'return true' to avoid reference count leak.

Fixes: 89a6079df791 ("iommu/vt-d: Force IOMMU on for platform opt in hint")
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>
Link: https://lore.kernel.org/r/20221121113649.190393-2-wangxiongfeng2@huawei.com
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 587eebe39820..5287efe247b1 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3873,8 +3873,10 @@ static inline bool has_external_pci(void)
 	struct pci_dev *pdev = NULL;
 
 	for_each_pci_dev(pdev)
-		if (pdev->external_facing)
+		if (pdev->external_facing) {
+			pci_dev_put(pdev);
 			return true;
+		}
 
 	return false;
 }
-- 
2.34.1