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, 50 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
new file mode 100644
index 000000000..22f28f2e9
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
@@ -0,0 +1,50 @@
+What:		/sys/class/leds/<led>/pattern
+Date:		September 2018
+KernelVersion:	4.20
+Description:
+		Specify a software pattern for the LED, that supports altering
+		the brightness for the specified duration with one software
+		timer. It can do gradual dimming and step change of brightness.
+
+		The pattern is given by a series of tuples, of brightness and
+		duration (ms).
+
+		The exact format is described in:
+		Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt
+
+What:		/sys/class/leds/<led>/hr_pattern
+Date:		April 2024
+Description:
+		Specify a software pattern for the LED, that supports altering
+		the brightness for the specified duration with one software
+		timer. It can do gradual dimming and step change of brightness.
+
+		Unlike the /sys/class/leds/<led>/pattern, this attribute runs
+		a pattern on high-resolution timer (hrtimer).
+
+What:		/sys/class/leds/<led>/hw_pattern
+Date:		September 2018
+KernelVersion:	4.20
+Description:
+		Specify a hardware pattern for the LED, for LED hardware that
+		supports autonomously controlling brightness over time, according
+		to some preprogrammed hardware patterns. It deactivates any active
+		software pattern.
+
+		Since different LED hardware can have different semantics of
+		hardware patterns, each driver is expected to provide its own
+		description for the hardware patterns in their documentation
+		file at Documentation/leds/.
+
+What:		/sys/class/leds/<led>/repeat
+Date:		September 2018
+KernelVersion:	4.20
+Description:
+		Specify a pattern repeat number. -1 means repeat indefinitely,
+		other negative numbers and number 0 are invalid.
+
+		This file will always return the originally written repeat
+		number.
+
+		It should be noticed that some leds, like EL15203000 may
+		only support indefinitely patterns, so they always store -1.