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>

3 files changed, 126 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/trigger-source/adi,util-sigma-delta-spi.yaml b/Documentation/devicetree/bindings/trigger-source/adi,util-sigma-delta-spi.yaml
new file mode 100644
index 000000000..ea4661795
--- /dev/null
+++ b/Documentation/devicetree/bindings/trigger-source/adi,util-sigma-delta-spi.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (c) 2025 Analog Devices, Inc.
+# Copyright (c) 2025 BayLibre, SAS
+
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/adi,util-sigma-delta-spi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices Util Sigma-Delta SPI IP Core
+
+maintainers:
+  - David Lechner <dlechner@baylibre.com>
+
+description:
+  The Util Sigma-Delta SPI is an FPGA IP core from Analog Devices that provides
+  a SPI offload trigger from the RDY signal of the combined DOUT/RDY pin of
+  the sigma-delta family of ADCs.
+  https://analogdevicesinc.github.io/hdl/library/util_sigma_delta_spi/index.html
+
+properties:
+  compatible:
+    const: adi,util-sigma-delta-spi
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  '#trigger-source-cells':
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - '#trigger-source-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    trigger@40000 {
+        reg = <0x40000 0x1000>;
+        compatible = "adi,util-sigma-delta-spi";
+        clocks = <&clk 0>;
+        #trigger-source-cells = <0>;
+    };
diff --git a/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
new file mode 100644
index 000000000..1331d153e
--- /dev/null
+++ b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/gpio-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using GPIO
+
+description: A GPIO used as a trigger source.
+
+maintainers:
+  - Jonathan Santos <Jonathan.Santos@analog.com>
+
+properties:
+  compatible:
+    const: gpio-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  gpios:
+    maxItems: 1
+    description: GPIO to be used as a trigger source.
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    trigger {
+        compatible = "gpio-trigger";
+        #trigger-source-cells = <0>;
+        gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>;
+    };
diff --git a/Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml b/Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
new file mode 100644
index 000000000..1eac20031
--- /dev/null
+++ b/Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/pwm-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using PWM
+
+description: Remaps a PWM channel as a trigger source.
+
+maintainers:
+  - David Lechner <dlechner@baylibre.com>
+
+properties:
+  compatible:
+    const: pwm-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  pwms:
+    maxItems: 1
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - pwms
+
+additionalProperties: false
+
+examples:
+  - |
+    trigger {
+        compatible = "pwm-trigger";
+        #trigger-source-cells = <0>;
+        pwms = <&pwm 0 1000000 0>;
+    };