[PATCH 6.6.y] iommu/sva: Set handle->dev before the SVA handle is visible

[Sasha Levin <sashal@kernel.org>]

From: Shuai Xue <xueshuai@linux.alibaba.com>

[ Upstream commit 530f8f9c3546cb3ebee1b135375aaee08a073ebb ]

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@vger.kernel.org
Assisted-by: Qoder:Qwen-3.8-MAX-Preview
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
[ Adjusted context for per-bind SVA handles lacking handle->users reference counting. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 a340b805b82b7..4605304410be1 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -100,8 +100,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 		goto out_free_domain;
 	domain->users = 1;
 out:
-	mutex_unlock(&iommu_sva_lock);
 	handle->dev = dev;
+	mutex_unlock(&iommu_sva_lock);
 	handle->domain = domain;
 
 	return handle;
-- 
2.53.0