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, 67 insertions, 0 deletions

diff --git a/Documentation/driver-api/w1.rst b/Documentation/driver-api/w1.rst
new file mode 100644
index 000000000..bda3ad60f
--- /dev/null
+++ b/Documentation/driver-api/w1.rst
@@ -0,0 +1,67 @@
+======================
+W1: Dallas' 1-wire bus
+======================
+
+:Author: David Fries
+
+W1 API internal to the kernel
+=============================
+
+include/linux/w1.h
+~~~~~~~~~~~~~~~~~~
+
+W1 kernel API functions.
+
+.. kernel-doc:: include/linux/w1.h
+   :internal:
+
+drivers/w1/w1.c
+~~~~~~~~~~~~~~~
+
+W1 core functions.
+
+.. kernel-doc:: drivers/w1/w1.c
+   :internal:
+
+drivers/w1/w1_family.c
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Allows registering device family operations.
+
+.. kernel-doc:: drivers/w1/w1_family.c
+   :export:
+
+drivers/w1/w1_internal.h
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+W1 internal initialization for master devices.
+
+.. kernel-doc:: drivers/w1/w1_internal.h
+   :internal:
+
+drivers/w1/w1_int.c
+~~~~~~~~~~~~~~~~~~~~
+
+W1 internal initialization for master devices.
+
+.. kernel-doc:: drivers/w1/w1_int.c
+   :export:
+
+drivers/w1/w1_netlink.h
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+W1 external netlink API structures and commands.
+
+.. kernel-doc:: drivers/w1/w1_netlink.h
+   :internal:
+
+drivers/w1/w1_io.c
+~~~~~~~~~~~~~~~~~~~
+
+W1 input/output.
+
+.. kernel-doc:: drivers/w1/w1_io.c
+   :export:
+
+.. kernel-doc:: drivers/w1/w1_io.c
+   :internal: