This is a note to let you know that I've just added the patch titled
iommufd: Fix locking around hwpt allocation
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommufd-fix-locking-around-hwpt-allocation.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ece01f584b5c50b8b187a17b7cf786fcba2184c5
Author: Jason Gunthorpe <jgg@xxxxxxxx>
Date: Mon Jul 17 15:12:07 2023 -0300
iommufd: Fix locking around hwpt allocation
[ Upstream commit 31422dff187b243c58f3a97d16bbe9e9ada639fe ]
Due to the auto_domains mechanism the ioas->mutex must be held until
the hwpt is completely setup by iommufd_object_abort_and_destroy() or
iommufd_object_finalize().
This prevents a concurrent iommufd_device_auto_get_domain() from seeing
an incompletely initialized object through the ioas->hwpt_list.
To make this more consistent move the unlock until after finalize.
Fixes: e8d57210035b ("iommufd: Add kAPI toward external drivers for physical devices")
Link: https://lore.kernel.org/r/11-v8-6659224517ea+532-iommufd_alloc_jgg@xxxxxxxxxx
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index ed2937a4e196f..2e43ebf1a2b5c 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -298,8 +298,8 @@ static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
}
hwpt->auto_domain = true;
- mutex_unlock(&ioas->mutex);
iommufd_object_finalize(idev->ictx, &hwpt->obj);
+ mutex_unlock(&ioas->mutex);
return 0;
out_unlock:
mutex_unlock(&ioas->mutex);
