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, 45 insertions, 0 deletions

diff --git a/arch/m68k/Kconfig.debug b/arch/m68k/Kconfig.debug
new file mode 100644
index 000000000..d036f9038
--- /dev/null
+++ b/arch/m68k/Kconfig.debug
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config BOOTPARAM
+	bool "Compiled-in Kernel Boot Parameter"
+
+config BOOTPARAM_STRING
+	string "Kernel Boot Parameter"
+	default "console=ttyS0,19200"
+	depends on BOOTPARAM
+
+config EARLY_PRINTK
+	bool "Early printk"
+	depends on MMU_MOTOROLA
+	help
+	  Write kernel log output directly to a serial port.
+	  Where implemented, output goes to the framebuffer as well.
+	  PROM console functionality on Sun 3x is not affected by this option.
+
+	  Pass "earlyprintk" on the kernel command line to get a
+	  boot console.
+
+	  This is useful for kernel debugging when your machine crashes very
+	  early, i.e. before the normal console driver is loaded.
+	  You should normally say N here, unless you want to debug such a crash.
+
+if !MMU
+
+config FULLDEBUG
+	bool "Full Symbolic/Source Debugging support"
+	help
+	  Enable debugging symbols on kernel build.
+
+config HIGHPROFILE
+	bool "Use fast second timer for profiling"
+	depends on COLDFIRE
+	help
+	  Use a fast secondary clock to produce profiling information.
+
+config BDM_DISABLE
+	bool "Disable BDM signals"
+	depends on COLDFIRE
+	help
+	  Disable the ColdFire CPU's BDM signals.
+
+endif