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>

1 files changed, 57 insertions, 0 deletions

diff --git a/Documentation/devicetree/kernel-api.rst b/Documentation/devicetree/kernel-api.rst
new file mode 100644
index 000000000..b7429e6ed
--- /dev/null
+++ b/Documentation/devicetree/kernel-api.rst
@@ -0,0 +1,57 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. _devicetree:
+
+======================================
+DeviceTree Kernel API
+======================================
+
+Core functions
+--------------
+
+.. kernel-doc:: drivers/of/base.c
+   :export:
+
+.. kernel-doc:: include/linux/of.h
+   :internal:
+
+.. kernel-doc:: drivers/of/property.c
+   :export:
+
+.. kernel-doc:: include/linux/of_graph.h
+   :internal:
+
+.. kernel-doc:: drivers/of/address.c
+   :export:
+
+.. kernel-doc:: drivers/of/irq.c
+   :export:
+
+.. kernel-doc:: drivers/of/fdt.c
+   :export:
+
+Driver model functions
+----------------------
+
+.. kernel-doc:: include/linux/of_device.h
+   :internal:
+
+.. kernel-doc:: drivers/of/device.c
+   :export:
+
+.. kernel-doc:: include/linux/of_platform.h
+   :internal:
+
+.. kernel-doc:: drivers/of/platform.c
+   :export:
+
+Overlay and Dynamic DT functions
+--------------------------------
+
+.. kernel-doc:: drivers/of/resolver.c
+   :export:
+
+.. kernel-doc:: drivers/of/dynamic.c
+   :export:
+
+.. kernel-doc:: drivers/of/overlay.c
+   :export: