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, 93 insertions, 0 deletions

diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
new file mode 100644
index 000000000..3c76a5bf6
--- /dev/null
+++ b/drivers/base/regmap/Kconfig
@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: GPL-2.0
+# Generic register map support.  There are no user servicable options here,
+# this is an API intended to be used by other kernel subsystems.  These
+# subsystems should select the appropriate symbols.
+
+config REGMAP
+	bool
+	default y if (REGMAP_I2C || REGMAP_SLIMBUS || REGMAP_SPI || REGMAP_SPMI || REGMAP_W1 || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ || REGMAP_SOUNDWIRE || REGMAP_SOUNDWIRE_MBQ || REGMAP_SCCB || REGMAP_I3C || REGMAP_SPI_AVMM || REGMAP_MDIO || REGMAP_FSI)
+	help
+	  Enable support for the Register Map (regmap) access API.
+
+	  Usually, this option is automatically selected when needed.
+	  However, you may want to enable it manually for running the regmap
+	  KUnit tests.
+
+	  If unsure, say N.
+
+config REGMAP_KUNIT
+	tristate "KUnit tests for regmap"
+	depends on KUNIT && REGMAP
+	default KUNIT_ALL_TESTS
+	select REGMAP_RAM
+
+config REGMAP_BUILD
+	bool "Enable regmap build"
+	depends on KUNIT
+	select REGMAP
+	help
+	  This option exists purely to allow the regmap KUnit tests to
+	  be enabled without having to enable some driver that uses
+	  regmap due to unfortunate issues with how KUnit tests are
+	  normally enabled.
+
+config REGMAP_AC97
+	tristate
+
+config REGMAP_I2C
+	tristate
+	depends on I2C
+
+config REGMAP_SLIMBUS
+	tristate
+	depends on SLIMBUS
+
+config REGMAP_SPI
+	tristate
+	depends on SPI
+
+config REGMAP_SPMI
+	tristate
+	depends on SPMI
+
+config REGMAP_W1
+	tristate
+	depends on W1
+
+config REGMAP_MDIO
+	tristate
+	depends on PHYLIB
+
+config REGMAP_MMIO
+	tristate
+
+config REGMAP_IRQ
+	bool
+	select IRQ_DOMAIN
+
+config REGMAP_RAM
+	tristate
+
+config REGMAP_SOUNDWIRE
+	tristate
+	depends on SOUNDWIRE
+
+config REGMAP_SOUNDWIRE_MBQ
+	tristate
+	depends on SOUNDWIRE
+
+config REGMAP_SCCB
+	tristate
+	depends on I2C
+
+config REGMAP_I3C
+	tristate
+	depends on I3C
+
+config REGMAP_SPI_AVMM
+	tristate
+	depends on SPI
+
+config REGMAP_FSI
+	tristate
+	depends on FSI