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, 43 insertions, 0 deletions

diff --git a/samples/damon/Kconfig b/samples/damon/Kconfig
new file mode 100644
index 000000000..00be3e6bd
--- /dev/null
+++ b/samples/damon/Kconfig
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "DAMON Samples"
+
+config SAMPLE_DAMON_WSSE
+	bool "DAMON sample module for working set size estimation"
+	depends on DAMON && DAMON_VADDR
+	help
+	  This builds DAMON sample module for working set size estimation.
+
+	  The module receives a pid, monitor access to the virtual address
+	  space of the process, estimate working set size of the process, and
+	  repeatedly prints the size on the kernel log.
+
+	  If unsure, say N.
+
+config SAMPLE_DAMON_PRCL
+	bool "DAMON sample module for access-aware proactive reclamation"
+	depends on DAMON && DAMON_VADDR
+	help
+	  This builds DAMON sample module for access-aware proactive
+	  reclamation.
+
+	  The module receives a pid, monitor access to the virtual address
+	  space of the process, find memory regions that not accessed, and
+	  proactively reclaim the regions.
+
+	  If unsure, say N.
+
+config SAMPLE_DAMON_MTIER
+	bool "DAMON sample module for memory tiering"
+	depends on DAMON && DAMON_PADDR
+	help
+	  This builds DAMON sample module for memory tiering.
+
+	  The module assumes the system is constructed with two NUMA nodes,
+	  which seems as local and remote nodes to all CPUs.  For example,
+	  node0 is for DDR5 DRAMs connected via DIMM, while node1 is for DDR4
+	  DRAMs connected via CXL.
+
+	  If unsure, say N.
+
+endmenu