dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel()grafted

When dma_device_put() drops the last reference on chan->device->ref,
dma_device_release() runs and may free the dma_device along with its
channels.

dma_chan_put() then still reads chan->device->owner via
dma_chan_to_owner() for the trailing module_put(). KASAN catches it:

	slab-use-after-free in dma_chan_put+0x3e6/0x4c0
	Read of size 8 by task insmod/6319
	Freed by task 6319:
	  kfree+0x225/0x470
	  dma_chan_put+0x395/0x4c0
	  dmaengine_put+0xf8/0x160

Cache the module owner in dma_chan_put() before the put so the trailing
module_put() does not need chan->device.

Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct")
Suggested-by: Sashiko <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

2 files changed, 184 insertions, 0 deletions

diff --git a/Documentation/gpu/imagination/index.rst b/Documentation/gpu/imagination/index.rst
new file mode 100644
index 000000000..0c1e247ce
--- /dev/null
+++ b/Documentation/gpu/imagination/index.rst
@@ -0,0 +1,13 @@
+=======================================
+drm/imagination PowerVR Graphics Driver
+=======================================
+
+.. kernel-doc:: drivers/gpu/drm/imagination/pvr_drv.c
+   :doc: PowerVR (Series 6 and later) and IMG Graphics Driver
+
+Contents
+========
+.. toctree::
+   :maxdepth: 2
+
+   uapi
diff --git a/Documentation/gpu/imagination/uapi.rst b/Documentation/gpu/imagination/uapi.rst
new file mode 100644
index 000000000..7502413d0
--- /dev/null
+++ b/Documentation/gpu/imagination/uapi.rst
@@ -0,0 +1,171 @@
+====
+UAPI
+====
+The sources associated with this section can be found in ``pvr_drm.h``.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR UAPI
+
+OBJECT ARRAYS
+=============
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_obj_array
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: DRM_PVR_OBJ_ARRAY
+
+IOCTLS
+======
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL interface
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: PVR_IOCTL
+
+DEV_QUERY
+---------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL DEV_QUERY interface
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_dev_query
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_dev_query_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_dev_query_gpu_info
+                 drm_pvr_dev_query_runtime_info
+                 drm_pvr_dev_query_hwrt_info
+                 drm_pvr_dev_query_quirks
+                 drm_pvr_dev_query_enhancements
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_heap_id
+                 drm_pvr_heap
+                 drm_pvr_dev_query_heap_info
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_static_data_area_usage
+                 drm_pvr_static_data_area
+                 drm_pvr_dev_query_static_data_areas
+
+CREATE_BO
+---------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL CREATE_BO interface
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_create_bo_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for CREATE_BO
+
+GET_BO_MMAP_OFFSET
+------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL GET_BO_MMAP_OFFSET interface
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_get_bo_mmap_offset_args
+
+CREATE_VM_CONTEXT and DESTROY_VM_CONTEXT
+----------------------------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL CREATE_VM_CONTEXT and DESTROY_VM_CONTEXT interfaces
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_create_vm_context_args
+                 drm_pvr_ioctl_destroy_vm_context_args
+
+VM_MAP and VM_UNMAP
+-------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL VM_MAP and VM_UNMAP interfaces
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_vm_map_args
+                 drm_pvr_ioctl_vm_unmap_args
+
+CREATE_CONTEXT and DESTROY_CONTEXT
+----------------------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL CREATE_CONTEXT and DESTROY_CONTEXT interfaces
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_create_context_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ctx_priority
+                 drm_pvr_ctx_type
+                 drm_pvr_static_render_context_state
+                 drm_pvr_static_render_context_state_format
+                 drm_pvr_reset_framework
+                 drm_pvr_reset_framework_format
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_destroy_context_args
+
+CREATE_FREE_LIST and DESTROY_FREE_LIST
+--------------------------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL CREATE_FREE_LIST and DESTROY_FREE_LIST interfaces
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_create_free_list_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_destroy_free_list_args
+
+CREATE_HWRT_DATASET and DESTROY_HWRT_DATASET
+--------------------------------------------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL CREATE_HWRT_DATASET and DESTROY_HWRT_DATASET interfaces
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_create_hwrt_dataset_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_create_hwrt_geom_data_args
+                 drm_pvr_create_hwrt_rt_data_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_destroy_hwrt_dataset_args
+
+SUBMIT_JOBS
+-----------
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: PowerVR IOCTL SUBMIT_JOBS interface
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for the drm_pvr_sync_op object.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_ioctl_submit_jobs_args
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for SUBMIT_JOB ioctl geometry command.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for SUBMIT_JOB ioctl fragment command.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for SUBMIT_JOB ioctl compute command.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :doc: Flags for SUBMIT_JOB ioctl transfer command.
+
+.. kernel-doc:: include/uapi/drm/pvr_drm.h
+   :identifiers: drm_pvr_sync_op
+                 drm_pvr_job_type
+                 drm_pvr_hwrt_data_ref
+                 drm_pvr_job
+
+Internal notes
+==============
+.. kernel-doc:: drivers/gpu/drm/imagination/pvr_device.h
+   :doc: IOCTL validation helpers
+
+.. kernel-doc:: drivers/gpu/drm/imagination/pvr_device.h
+   :identifiers: PVR_STATIC_ASSERT_64BIT_ALIGNED PVR_IOCTL_UNION_PADDING_CHECK
+                 pvr_ioctl_union_padding_check