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, 48 insertions, 0 deletions

diff --git a/include/soc/qcom/cmd-db.h b/include/soc/qcom/cmd-db.h
new file mode 100644
index 000000000..47a6cab75
--- /dev/null
+++ b/include/soc/qcom/cmd-db.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2024, Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#ifndef __QCOM_COMMAND_DB_H__
+#define __QCOM_COMMAND_DB_H__
+
+#include <linux/err.h>
+
+enum cmd_db_hw_type {
+	CMD_DB_HW_INVALID = 0,
+	CMD_DB_HW_MIN     = 3,
+	CMD_DB_HW_ARC     = CMD_DB_HW_MIN,
+	CMD_DB_HW_VRM     = 4,
+	CMD_DB_HW_BCM     = 5,
+	CMD_DB_HW_MAX     = CMD_DB_HW_BCM,
+	CMD_DB_HW_ALL     = 0xff,
+};
+
+#if IS_ENABLED(CONFIG_QCOM_COMMAND_DB)
+u32 cmd_db_read_addr(const char *resource_id);
+
+const void *cmd_db_read_aux_data(const char *resource_id, size_t *len);
+
+bool cmd_db_match_resource_addr(u32 addr1, u32 addr2);
+
+enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id);
+
+int cmd_db_ready(void);
+#else
+static inline u32 cmd_db_read_addr(const char *resource_id)
+{ return 0; }
+
+static inline const void *cmd_db_read_aux_data(const char *resource_id, size_t *len)
+{ return ERR_PTR(-ENODEV); }
+
+static inline bool cmd_db_match_resource_addr(u32 addr1, u32 addr2)
+{ return false; }
+
+static inline enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id)
+{ return -ENODEV; }
+
+static inline int cmd_db_ready(void)
+{ return -ENODEV; }
+#endif /* CONFIG_QCOM_COMMAND_DB */
+#endif /* __QCOM_COMMAND_DB_H__ */