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, 55 insertions, 0 deletions

diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
new file mode 100644
index 000000000..fd0df604e
--- /dev/null
+++ b/fs/dlm/lowcomms.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
+**
+**
+*******************************************************************************
+******************************************************************************/
+
+#ifndef __LOWCOMMS_DOT_H__
+#define __LOWCOMMS_DOT_H__
+
+#include "dlm_internal.h"
+
+#define DLM_MIDCOMMS_OPT_LEN		sizeof(struct dlm_opts)
+#define DLM_MAX_APP_BUFSIZE		(DLM_MAX_SOCKET_BUFSIZE - \
+					 DLM_MIDCOMMS_OPT_LEN)
+
+#define CONN_HASH_SIZE 32
+
+/* This is deliberately very simple because most clusters have simple
+ * sequential nodeids, so we should be able to go straight to a connection
+ * struct in the array
+ */
+static inline int nodeid_hash(int nodeid)
+{
+	return nodeid & (CONN_HASH_SIZE-1);
+}
+
+/* check if dlm is running */
+bool dlm_lowcomms_is_running(void);
+
+int dlm_lowcomms_start(void);
+void dlm_lowcomms_shutdown(void);
+void dlm_lowcomms_shutdown_node(int nodeid, bool force);
+void dlm_lowcomms_stop(void);
+void dlm_lowcomms_init(void);
+void dlm_lowcomms_exit(void);
+int dlm_lowcomms_close(int nodeid);
+struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int len, char **ppc,
+				     void (*cb)(void *data), void *data);
+void dlm_lowcomms_commit_msg(struct dlm_msg *msg);
+void dlm_lowcomms_put_msg(struct dlm_msg *msg);
+int dlm_lowcomms_resend_msg(struct dlm_msg *msg);
+int dlm_lowcomms_connect_node(int nodeid);
+int dlm_lowcomms_nodes_set_mark(int nodeid, unsigned int mark);
+int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr);
+void dlm_midcomms_receive_done(int nodeid);
+struct kmem_cache *dlm_lowcomms_writequeue_cache_create(void);
+struct kmem_cache *dlm_lowcomms_msg_cache_create(void);
+
+#endif				/* __LOWCOMMS_DOT_H__ */
+