[PATCH 1/4] iommu/sva: Set handle->dev before the SVA handle is visible

[Shuai Xue]

iommu_attach_device_pasid() installs the new SVA attach handle in the
group PASID lookup before iommu_sva_bind_device() returns. A concurrent
bind can therefore find and reuse the same handle after iommu_sva_lock is
dropped.

handle->dev was initialized after dropping iommu_sva_lock. This leaves a
window where a racing bind can return a handle whose dev pointer is still
NULL. A subsequent iommu_sva_unbind_device() can then dereference it via
handle->dev->iommu_group.

Initialize handle->dev before releasing iommu_sva_lock so any visible SVA
handle is fully initialized.

Fixes: be51b1d6bbff ("iommu/sva: Refactoring iommu_sva_bind/unbind_device()")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: Qoder:Qwen-3.8-MAX-Preview
Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
---
 drivers/iommu/iommu-sva.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index bc7c7232a43e..9742cb593577 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -145,8 +145,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 	list_add(&domain->next, &iommu_mm->sva_domains);
 out:
 	refcount_set(&handle->users, 1);
-	mutex_unlock(&iommu_sva_lock);
 	handle->dev = dev;
+	mutex_unlock(&iommu_sva_lock);
 	return handle;
 
 out_free_domain:
-- 
2.39.3