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* [PATCH v2] iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE
@ 2024-11-15 18:46 Kees Bakker
  2025-01-02  3:11 ` Baolu Lu
  0 siblings, 1 reply; 2+ messages in thread
From: Kees Bakker @ 2024-11-15 18:46 UTC (permalink / raw)
  To: Baolu Lu, iommu, Tian Kevin, Joerg Roedel, Will Deacon, Robin Murphy
  Cc: linux-kernel

There is a WARN_ON_ONCE to catch an unlikely situation when
domain_remove_dev_pasid can't find the `pasid`. In case it nevertheless
happens we must avoid using a NULL pointer.

Signed-off-by: Kees Bakker <kees@ijzerbout.nl>
---
 v1 -> v2: change subject to use 'iommu/vt-d:' prefix

 drivers/iommu/intel/iommu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 82ee86d86a93..e933c84faf0b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4089,13 +4089,14 @@ void domain_remove_dev_pasid(struct iommu_domain *domain,
 			break;
 		}
 	}
-	WARN_ON_ONCE(!dev_pasid);
 	spin_unlock_irqrestore(&dmar_domain->lock, flags);
 
 	cache_tag_unassign_domain(dmar_domain, dev, pasid);
 	domain_detach_iommu(dmar_domain, iommu);
-	intel_iommu_debugfs_remove_dev_pasid(dev_pasid);
-	kfree(dev_pasid);
+	if (!WARN_ON_ONCE(!dev_pasid)) {
+		intel_iommu_debugfs_remove_dev_pasid(dev_pasid);
+		kfree(dev_pasid);
+	}
 }
 
 static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,
-- 
2.47.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2024-11-15 18:46 [PATCH v2] iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE Kees Bakker
2025-01-02  3:11 ` Baolu Lu

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