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, 122 insertions, 0 deletions

diff --git a/drivers/input/apm-power.c b/drivers/input/apm-power.c
new file mode 100644
index 000000000..028fcaf4c
--- /dev/null
+++ b/drivers/input/apm-power.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Input Power Event -> APM Bridge
+ *
+ *  Copyright (c) 2007 Richard Purdie
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/delay.h>
+#include <linux/pm.h>
+#include <linux/apm-emulation.h>
+
+static void system_power_event(unsigned int keycode)
+{
+	switch (keycode) {
+	case KEY_SUSPEND:
+		apm_queue_event(APM_USER_SUSPEND);
+		pr_info("Requesting system suspend...\n");
+		break;
+	default:
+		break;
+	}
+}
+
+static void apmpower_event(struct input_handle *handle, unsigned int type,
+			   unsigned int code, int value)
+{
+	/* only react on key down events */
+	if (value != 1)
+		return;
+
+	switch (type) {
+	case EV_PWR:
+		system_power_event(code);
+		break;
+
+	default:
+		break;
+	}
+}
+
+static int apmpower_connect(struct input_handler *handler,
+					  struct input_dev *dev,
+					  const struct input_device_id *id)
+{
+	struct input_handle *handle;
+	int error;
+
+	handle = kzalloc_obj(struct input_handle);
+	if (!handle)
+		return -ENOMEM;
+
+	handle->dev = dev;
+	handle->handler = handler;
+	handle->name = "apm-power";
+
+	error = input_register_handle(handle);
+	if (error) {
+		pr_err("Failed to register input power handler, error %d\n",
+		       error);
+		kfree(handle);
+		return error;
+	}
+
+	error = input_open_device(handle);
+	if (error) {
+		pr_err("Failed to open input power device, error %d\n", error);
+		input_unregister_handle(handle);
+		kfree(handle);
+		return error;
+	}
+
+	return 0;
+}
+
+static void apmpower_disconnect(struct input_handle *handle)
+{
+	input_close_device(handle);
+	input_unregister_handle(handle);
+	kfree(handle);
+}
+
+static const struct input_device_id apmpower_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+		.evbit = { BIT_MASK(EV_PWR) },
+	},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(input, apmpower_ids);
+
+static struct input_handler apmpower_handler = {
+	.event =	apmpower_event,
+	.connect =	apmpower_connect,
+	.disconnect =	apmpower_disconnect,
+	.name =		"apm-power",
+	.id_table =	apmpower_ids,
+};
+
+static int __init apmpower_init(void)
+{
+	return input_register_handler(&apmpower_handler);
+}
+
+static void __exit apmpower_exit(void)
+{
+	input_unregister_handler(&apmpower_handler);
+}
+
+module_init(apmpower_init);
+module_exit(apmpower_exit);
+
+MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
+MODULE_DESCRIPTION("Input Power Event -> APM Bridge");
+MODULE_LICENSE("GPL");