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, 185 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/dynapro.c b/drivers/input/touchscreen/dynapro.c
new file mode 100644
index 000000000..943ba8c2f
--- /dev/null
+++ b/drivers/input/touchscreen/dynapro.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Dynapro serial touchscreen driver
+ *
+ * Copyright (c) 2009 Tias Guns
+ * Based on the inexio driver (c) Vojtech Pavlik and Dan Streetman and
+ * Richard Lemon
+ */
+
+
+/*
+ * 2009/09/19 Tias Guns <tias@ulyssis.org>
+ *   Copied inexio.c and edited for Dynapro protocol (from retired Xorg module)
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Dynapro serial touchscreen driver"
+
+MODULE_AUTHOR("Tias Guns <tias@ulyssis.org>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define DYNAPRO_FORMAT_TOUCH_BIT 0x40
+#define DYNAPRO_FORMAT_LENGTH 3
+#define DYNAPRO_RESPONSE_BEGIN_BYTE 0x80
+
+#define DYNAPRO_MIN_XC 0
+#define DYNAPRO_MAX_XC 0x3ff
+#define DYNAPRO_MIN_YC 0
+#define DYNAPRO_MAX_YC 0x3ff
+
+#define DYNAPRO_GET_XC(data) (data[1] | ((data[0] & 0x38) << 4))
+#define DYNAPRO_GET_YC(data) (data[2] | ((data[0] & 0x07) << 7))
+#define DYNAPRO_GET_TOUCHED(data) (DYNAPRO_FORMAT_TOUCH_BIT & data[0])
+
+/*
+ * Per-touchscreen data.
+ */
+
+struct dynapro {
+	struct input_dev *dev;
+	struct serio *serio;
+	int idx;
+	unsigned char data[DYNAPRO_FORMAT_LENGTH];
+	char phys[32];
+};
+
+static void dynapro_process_data(struct dynapro *pdynapro)
+{
+	struct input_dev *dev = pdynapro->dev;
+
+	if (DYNAPRO_FORMAT_LENGTH == ++pdynapro->idx) {
+		input_report_abs(dev, ABS_X, DYNAPRO_GET_XC(pdynapro->data));
+		input_report_abs(dev, ABS_Y, DYNAPRO_GET_YC(pdynapro->data));
+		input_report_key(dev, BTN_TOUCH,
+				 DYNAPRO_GET_TOUCHED(pdynapro->data));
+		input_sync(dev);
+
+		pdynapro->idx = 0;
+	}
+}
+
+static irqreturn_t dynapro_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct dynapro *pdynapro = serio_get_drvdata(serio);
+
+	pdynapro->data[pdynapro->idx] = data;
+
+	if (DYNAPRO_RESPONSE_BEGIN_BYTE & pdynapro->data[0])
+		dynapro_process_data(pdynapro);
+	else
+		dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
+			pdynapro->data[0]);
+
+	return IRQ_HANDLED;
+}
+
+static void dynapro_disconnect(struct serio *serio)
+{
+	struct dynapro *pdynapro = serio_get_drvdata(serio);
+
+	input_get_device(pdynapro->dev);
+	input_unregister_device(pdynapro->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_put_device(pdynapro->dev);
+	kfree(pdynapro);
+}
+
+/*
+ * dynapro_connect() is the routine that is called when someone adds a
+ * new serio device that supports dynapro protocol and registers it as
+ * an input device. This is usually accomplished using inputattach.
+ */
+
+static int dynapro_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct dynapro *pdynapro;
+	struct input_dev *input_dev;
+	int err;
+
+	pdynapro = kzalloc_obj(*pdynapro);
+	input_dev = input_allocate_device();
+	if (!pdynapro || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	pdynapro->serio = serio;
+	pdynapro->dev = input_dev;
+	scnprintf(pdynapro->phys, sizeof(pdynapro->phys),
+		  "%s/input0", serio->phys);
+
+	input_dev->name = "Dynapro Serial TouchScreen";
+	input_dev->phys = pdynapro->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_DYNAPRO;
+	input_dev->id.product = 0;
+	input_dev->id.version = 0x0001;
+	input_dev->dev.parent = &serio->dev;
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+	input_set_abs_params(pdynapro->dev, ABS_X,
+			     DYNAPRO_MIN_XC, DYNAPRO_MAX_XC, 0, 0);
+	input_set_abs_params(pdynapro->dev, ABS_Y,
+			     DYNAPRO_MIN_YC, DYNAPRO_MAX_YC, 0, 0);
+
+	serio_set_drvdata(serio, pdynapro);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(pdynapro->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(pdynapro);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id dynapro_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_DYNAPRO,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, dynapro_serio_ids);
+
+static struct serio_driver dynapro_drv = {
+	.driver		= {
+		.name	= "dynapro",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= dynapro_serio_ids,
+	.interrupt	= dynapro_interrupt,
+	.connect	= dynapro_connect,
+	.disconnect	= dynapro_disconnect,
+};
+
+module_serio_driver(dynapro_drv);