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, 193 insertions, 0 deletions

diff --git a/drivers/bluetooth/btmrvl_debugfs.c b/drivers/bluetooth/btmrvl_debugfs.c
new file mode 100644
index 000000000..9b3e768c0
--- /dev/null
+++ b/drivers/bluetooth/btmrvl_debugfs.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Marvell Bluetooth driver: debugfs related functions
+ *
+ * Copyright (C) 2009, Marvell International Ltd.
+ **/
+
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "btmrvl_drv.h"
+
+struct btmrvl_debugfs_data {
+	struct dentry *config_dir;
+	struct dentry *status_dir;
+};
+
+static ssize_t btmrvl_hscfgcmd_write(struct file *file,
+			const char __user *ubuf, size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.hscfgcmd = result;
+
+	if (priv->btmrvl_dev.hscfgcmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+}
+
+static ssize_t btmrvl_hscfgcmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n",
+						priv->btmrvl_dev.hscfgcmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_hscfgcmd_fops = {
+	.read	= btmrvl_hscfgcmd_read,
+	.write	= btmrvl_hscfgcmd_write,
+	.open	= simple_open,
+	.llseek = default_llseek,
+};
+
+static ssize_t btmrvl_pscmd_write(struct file *file, const char __user *ubuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.pscmd = result;
+
+	if (priv->btmrvl_dev.pscmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+
+}
+
+static ssize_t btmrvl_pscmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n", priv->btmrvl_dev.pscmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_pscmd_fops = {
+	.read = btmrvl_pscmd_read,
+	.write = btmrvl_pscmd_write,
+	.open = simple_open,
+	.llseek = default_llseek,
+};
+
+static ssize_t btmrvl_hscmd_write(struct file *file, const char __user *ubuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.hscmd = result;
+	if (priv->btmrvl_dev.hscmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+}
+
+static ssize_t btmrvl_hscmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n", priv->btmrvl_dev.hscmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_hscmd_fops = {
+	.read	= btmrvl_hscmd_read,
+	.write	= btmrvl_hscmd_write,
+	.open	= simple_open,
+	.llseek = default_llseek,
+};
+
+void btmrvl_debugfs_init(struct hci_dev *hdev)
+{
+	struct btmrvl_private *priv = hci_get_drvdata(hdev);
+	struct btmrvl_debugfs_data *dbg;
+
+	if (!hdev->debugfs)
+		return;
+
+	dbg = kzalloc_obj(*dbg);
+	priv->debugfs_data = dbg;
+
+	if (!dbg) {
+		BT_ERR("Can not allocate memory for btmrvl_debugfs_data.");
+		return;
+	}
+
+	dbg->config_dir = debugfs_create_dir("config", hdev->debugfs);
+
+	debugfs_create_u8("psmode", 0644, dbg->config_dir,
+			  &priv->btmrvl_dev.psmode);
+	debugfs_create_file("pscmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_pscmd_fops);
+	debugfs_create_x16("gpiogap", 0644, dbg->config_dir,
+			   &priv->btmrvl_dev.gpio_gap);
+	debugfs_create_u8("hsmode", 0644, dbg->config_dir,
+			  &priv->btmrvl_dev.hsmode);
+	debugfs_create_file("hscmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_hscmd_fops);
+	debugfs_create_file("hscfgcmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_hscfgcmd_fops);
+
+	dbg->status_dir = debugfs_create_dir("status", hdev->debugfs);
+	debugfs_create_u8("curpsmode", 0444, dbg->status_dir,
+			  &priv->adapter->psmode);
+	debugfs_create_u8("psstate", 0444, dbg->status_dir,
+			  &priv->adapter->ps_state);
+	debugfs_create_u8("hsstate", 0444, dbg->status_dir,
+			  &priv->adapter->hs_state);
+	debugfs_create_u8("txdnldready", 0444, dbg->status_dir,
+			  &priv->btmrvl_dev.tx_dnld_rdy);
+}
+
+void btmrvl_debugfs_remove(struct hci_dev *hdev)
+{
+	struct btmrvl_private *priv = hci_get_drvdata(hdev);
+	struct btmrvl_debugfs_data *dbg = priv->debugfs_data;
+
+	if (!dbg)
+		return;
+
+	debugfs_remove_recursive(dbg->config_dir);
+	debugfs_remove_recursive(dbg->status_dir);
+
+	kfree(dbg);
+}