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, 92 insertions, 0 deletions

diff --git a/drivers/input/misc/retu-pwrbutton.c b/drivers/input/misc/retu-pwrbutton.c
new file mode 100644
index 000000000..64023ac08
--- /dev/null
+++ b/drivers/input/misc/retu-pwrbutton.c
@@ -0,0 +1,92 @@
+/*
+ * Retu power button driver.
+ *
+ * Copyright (C) 2004-2010 Nokia Corporation
+ *
+ * Original code written by Ari Saastamoinen, Juha Yrjölä and Felipe Balbi.
+ * Rewritten by Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/irq.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/retu.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+#define RETU_STATUS_PWRONX (1 << 5)
+
+static irqreturn_t retu_pwrbutton_irq(int irq, void *_pwr)
+{
+	struct input_dev *idev = _pwr;
+	struct retu_dev *rdev = input_get_drvdata(idev);
+	bool state;
+
+	state = !(retu_read(rdev, RETU_REG_STATUS) & RETU_STATUS_PWRONX);
+	input_report_key(idev, KEY_POWER, state);
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static int retu_pwrbutton_probe(struct platform_device *pdev)
+{
+	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
+	struct input_dev *idev;
+	int irq;
+	int error;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	idev = devm_input_allocate_device(&pdev->dev);
+	if (!idev)
+		return -ENOMEM;
+
+	idev->name = "retu-pwrbutton";
+	idev->dev.parent = &pdev->dev;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+	input_set_drvdata(idev, rdev);
+
+	error = devm_request_threaded_irq(&pdev->dev, irq,
+					  NULL, retu_pwrbutton_irq,
+					  IRQF_ONESHOT,
+					  "retu-pwrbutton", idev);
+	if (error)
+		return error;
+
+	error = input_register_device(idev);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static struct platform_driver retu_pwrbutton_driver = {
+	.probe		= retu_pwrbutton_probe,
+	.driver		= {
+		.name	= "retu-pwrbutton",
+	},
+};
+module_platform_driver(retu_pwrbutton_driver);
+
+MODULE_ALIAS("platform:retu-pwrbutton");
+MODULE_DESCRIPTION("Retu Power Button");
+MODULE_AUTHOR("Ari Saastamoinen");
+MODULE_AUTHOR("Felipe Balbi");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
+MODULE_LICENSE("GPL");