iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE

keestux · joergroedel · commit 60f030f7418d · 2025-01-07T09:30:50.000+01:00
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> Link: https://lore.kernel.org/r/20241218201048.E544818E57E@bout3.ijzerbout.nl Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
@@ -4090,13 +4090,14 @@ 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,

Original file line number	Diff line number	Diff line change
`@@ -4090,13 +4090,14 @@ void domain_remove_dev_pasid(struct iommu_domain *domain,`
`4090`	`4090`	`break;`
`4091`	`4091`	`}`
`4092`	`4092`	`}`
`4093`		`- WARN_ON_ONCE(!dev_pasid);`
`4094`	`4093`	`spin_unlock_irqrestore(&dmar_domain->lock, flags);`
`4095`	`4094`
`4096`	`4095`	`cache_tag_unassign_domain(dmar_domain, dev, pasid);`
`4097`	`4096`	`domain_detach_iommu(dmar_domain, iommu);`
`4098`		`- intel_iommu_debugfs_remove_dev_pasid(dev_pasid);`
`4099`		`- kfree(dev_pasid);`
	`4097`	`+ if (!WARN_ON_ONCE(!dev_pasid)) {`
	`4098`	`+ intel_iommu_debugfs_remove_dev_pasid(dev_pasid);`
	`4099`	`+ kfree(dev_pasid);`
	`4100`	`+ }`
`4100`	`4101`	`}`
`4101`	`4102`
`4102`	`4103`	`static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,`