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, 294 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
new file mode 100644
index 000000000..e35fd1f69
--- /dev/null
+++ b/drivers/extcon/extcon-usb-gpio.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/extcon/extcon-usb-gpio.c - USB GPIO extcon driver
+ *
+ * Copyright (C) 2015 Texas Instruments Incorporated - https://www.ti.com
+ * Author: Roger Quadros <rogerq@ti.com>
+ */
+
+#include <linux/extcon-provider.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/pinctrl/consumer.h>
+
+#define USB_GPIO_DEBOUNCE_MS	20	/* ms */
+
+struct usb_extcon_info {
+	struct device *dev;
+	struct extcon_dev *edev;
+
+	struct gpio_desc *id_gpiod;
+	struct gpio_desc *vbus_gpiod;
+	int id_irq;
+	int vbus_irq;
+
+	unsigned long debounce_jiffies;
+	struct delayed_work wq_detcable;
+};
+
+static const unsigned int usb_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+/*
+ * "USB" = VBUS and "USB-HOST" = !ID, so we have:
+ * Both "USB" and "USB-HOST" can't be set as active at the
+ * same time so if "USB-HOST" is active (i.e. ID is 0)  we keep "USB" inactive
+ * even if VBUS is on.
+ *
+ *  State              |    ID   |   VBUS
+ * ----------------------------------------
+ *  [1] USB            |    H    |    H
+ *  [2] none           |    H    |    L
+ *  [3] USB-HOST       |    L    |    H
+ *  [4] USB-HOST       |    L    |    L
+ *
+ * In case we have only one of these signals:
+ * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
+ * - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
+*/
+static void usb_extcon_detect_cable(struct work_struct *work)
+{
+	int id, vbus;
+	struct usb_extcon_info *info = container_of(to_delayed_work(work),
+						    struct usb_extcon_info,
+						    wq_detcable);
+
+	/* check ID and VBUS and update cable state */
+	id = info->id_gpiod ?
+		gpiod_get_value_cansleep(info->id_gpiod) : 1;
+	vbus = info->vbus_gpiod ?
+		gpiod_get_value_cansleep(info->vbus_gpiod) : id;
+
+	/* at first we clean states which are no longer active */
+	if (id)
+		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, false);
+	if (!vbus)
+		extcon_set_state_sync(info->edev, EXTCON_USB, false);
+
+	if (!id) {
+		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, true);
+	} else {
+		if (vbus)
+			extcon_set_state_sync(info->edev, EXTCON_USB, true);
+	}
+}
+
+static irqreturn_t usb_irq_handler(int irq, void *dev_id)
+{
+	struct usb_extcon_info *info = dev_id;
+
+	queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
+			   info->debounce_jiffies);
+
+	return IRQ_HANDLED;
+}
+
+static int usb_extcon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct usb_extcon_info *info;
+	int ret;
+
+	if (!np)
+		return -EINVAL;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->dev = dev;
+	info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id", GPIOD_IN);
+	info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus",
+						   GPIOD_IN);
+
+	if (!info->id_gpiod && !info->vbus_gpiod) {
+		dev_err(dev, "failed to get gpios\n");
+		return -ENODEV;
+	}
+
+	if (IS_ERR(info->id_gpiod))
+		return PTR_ERR(info->id_gpiod);
+
+	if (IS_ERR(info->vbus_gpiod))
+		return PTR_ERR(info->vbus_gpiod);
+
+	info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
+	if (IS_ERR(info->edev)) {
+		dev_err(dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	ret = devm_extcon_dev_register(dev, info->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to register extcon device\n");
+		return ret;
+	}
+
+	if (info->id_gpiod)
+		ret = gpiod_set_debounce(info->id_gpiod,
+					 USB_GPIO_DEBOUNCE_MS * 1000);
+	if (!ret && info->vbus_gpiod)
+		ret = gpiod_set_debounce(info->vbus_gpiod,
+					 USB_GPIO_DEBOUNCE_MS * 1000);
+
+	if (ret < 0)
+		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
+
+	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
+
+	if (info->id_gpiod) {
+		info->id_irq = gpiod_to_irq(info->id_gpiod);
+		if (info->id_irq < 0) {
+			dev_err(dev, "failed to get ID IRQ\n");
+			return info->id_irq;
+		}
+
+		ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
+						usb_irq_handler,
+						IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for ID IRQ\n");
+			return ret;
+		}
+	}
+
+	if (info->vbus_gpiod) {
+		info->vbus_irq = gpiod_to_irq(info->vbus_gpiod);
+		if (info->vbus_irq < 0) {
+			dev_err(dev, "failed to get VBUS IRQ\n");
+			return info->vbus_irq;
+		}
+
+		ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
+						usb_irq_handler,
+						IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for VBUS IRQ\n");
+			return ret;
+		}
+	}
+
+	platform_set_drvdata(pdev, info);
+	device_set_wakeup_capable(&pdev->dev, true);
+
+	/* Perform initial detection */
+	usb_extcon_detect_cable(&info->wq_detcable.work);
+
+	return 0;
+}
+
+static void usb_extcon_remove(struct platform_device *pdev)
+{
+	struct usb_extcon_info *info = platform_get_drvdata(pdev);
+
+	cancel_delayed_work_sync(&info->wq_detcable);
+	device_init_wakeup(&pdev->dev, false);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int usb_extcon_suspend(struct device *dev)
+{
+	struct usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_gpiod) {
+			ret = enable_irq_wake(info->id_irq);
+			if (ret)
+				return ret;
+		}
+		if (info->vbus_gpiod) {
+			ret = enable_irq_wake(info->vbus_irq);
+			if (ret) {
+				if (info->id_gpiod)
+					disable_irq_wake(info->id_irq);
+
+				return ret;
+			}
+		}
+	}
+
+	if (!device_may_wakeup(dev))
+		pinctrl_pm_select_sleep_state(dev);
+
+	return ret;
+}
+
+static int usb_extcon_resume(struct device *dev)
+{
+	struct usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (!device_may_wakeup(dev))
+		pinctrl_pm_select_default_state(dev);
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_gpiod) {
+			ret = disable_irq_wake(info->id_irq);
+			if (ret)
+				return ret;
+		}
+		if (info->vbus_gpiod) {
+			ret = disable_irq_wake(info->vbus_irq);
+			if (ret) {
+				if (info->id_gpiod)
+					enable_irq_wake(info->id_irq);
+
+				return ret;
+			}
+		}
+	}
+
+	queue_delayed_work(system_power_efficient_wq,
+			   &info->wq_detcable, 0);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(usb_extcon_pm_ops,
+			 usb_extcon_suspend, usb_extcon_resume);
+
+static const struct of_device_id usb_extcon_dt_match[] = {
+	{ .compatible = "linux,extcon-usb-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, usb_extcon_dt_match);
+
+static const struct platform_device_id usb_extcon_platform_ids[] = {
+	{ .name = "extcon-usb-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, usb_extcon_platform_ids);
+
+static struct platform_driver usb_extcon_driver = {
+	.probe		= usb_extcon_probe,
+	.remove		= usb_extcon_remove,
+	.driver		= {
+		.name	= "extcon-usb-gpio",
+		.pm	= &usb_extcon_pm_ops,
+		.of_match_table = usb_extcon_dt_match,
+	},
+	.id_table = usb_extcon_platform_ids,
+};
+
+module_platform_driver(usb_extcon_driver);
+
+MODULE_AUTHOR("Roger Quadros <rogerq@ti.com>");
+MODULE_DESCRIPTION("USB GPIO extcon driver");
+MODULE_LICENSE("GPL v2");