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, 54 insertions, 0 deletions

diff --git a/drivers/pinctrl/devicetree.h b/drivers/pinctrl/devicetree.h
new file mode 100644
index 000000000..def76aba9
--- /dev/null
+++ b/drivers/pinctrl/devicetree.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Internal interface to pinctrl device tree integration
+ *
+ * Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
+ */
+
+#include <linux/errno.h>
+
+struct device_node;
+struct of_phandle_args;
+
+struct pinctrl;
+struct pinctrl_dev;
+
+#ifdef CONFIG_OF
+
+void pinctrl_dt_free_maps(struct pinctrl *p);
+int pinctrl_dt_to_map(struct pinctrl *p, struct pinctrl_dev *pctldev);
+
+int pinctrl_count_index_with_args(const struct device_node *np,
+				  const char *list_name);
+
+int pinctrl_parse_index_with_args(const struct device_node *np,
+				  const char *list_name, int index,
+				  struct of_phandle_args *out_args);
+
+#else
+
+static inline int pinctrl_dt_to_map(struct pinctrl *p,
+				    struct pinctrl_dev *pctldev)
+{
+	return 0;
+}
+
+static inline void pinctrl_dt_free_maps(struct pinctrl *p)
+{
+}
+
+static inline int pinctrl_count_index_with_args(const struct device_node *np,
+						const char *list_name)
+{
+	return -ENODEV;
+}
+
+static inline int
+pinctrl_parse_index_with_args(const struct device_node *np,
+			      const char *list_name, int index,
+			      struct of_phandle_args *out_args)
+{
+	return -ENODEV;
+}
+
+#endif