If something holds a refcount then it is at risk of UAFing. For abort
paths we expect the caller to never share the object with a parallel
thread and to clean up any refcounts it obtained on its own.
Add the missing dec inside iommufd_hwpt_paging_alloc() during error unwind
by making iommufd_hw_pagetable_attach/detach() proper pairs.
Link: https://patch.msgid.link/r/2-v1-02cd136829df+31-iommufd_syz_fput_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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