[PATCH v2] iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE

From: Kees Bakker
Date: Wed Dec 18 2024 - 15:11:08 EST


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@xxxxxxxxxxxx>
---
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