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, 49 insertions, 0 deletions

diff --git a/Documentation/networking/alias.rst b/Documentation/networking/alias.rst
new file mode 100644
index 000000000..af7c5ee92
--- /dev/null
+++ b/Documentation/networking/alias.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========
+IP-Aliasing
+===========
+
+IP-aliases are an obsolete way to manage multiple IP-addresses/masks
+per interface. Newer tools such as iproute2 support multiple
+address/prefixes per interface, but aliases are still supported
+for backwards compatibility.
+
+An alias is formed by adding a colon and a string when running ifconfig.
+This string is usually numeric, but this is not a must.
+
+
+Alias creation
+==============
+
+Alias creation is done by 'magic' interface naming: eg. to create a
+200.1.1.1 alias for eth0 ...
+::
+
+  # ifconfig eth0:0 200.1.1.1  etc,etc....
+	~~ -> request alias #0 creation (if not yet exists) for eth0
+
+The corresponding route is also set up by this command.  Please note:
+The route always points to the base interface.
+
+
+Alias deletion
+==============
+
+The alias is removed by shutting the alias down::
+
+  # ifconfig eth0:0 down
+	~~~~~~~~~~ -> will delete alias
+
+
+Alias (re-)configuring
+======================
+
+Aliases are not real devices, but programs should be able to configure
+and refer to them as usual (ifconfig, route, etc).
+
+
+Relationship with main device
+=============================
+
+If the base device is shut down the added aliases will be deleted too.