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, 63 insertions, 0 deletions

diff --git a/fs/smb/server/misc.h b/fs/smb/server/misc.h
new file mode 100644
index 000000000..1faaddd0f
--- /dev/null
+++ b/fs/smb/server/misc.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __KSMBD_MISC_H__
+#define __KSMBD_MISC_H__
+
+#ifdef CONFIG_PROC_FS
+#include <linux/proc_fs.h>
+#endif
+struct ksmbd_share_config;
+struct nls_table;
+struct kstat;
+struct ksmbd_file;
+
+int match_pattern(const char *str, size_t len, const char *pattern);
+int ksmbd_validate_filename(char *filename);
+int parse_stream_name(char *filename, char **stream_name, int *s_type);
+char *convert_to_nt_pathname(struct ksmbd_share_config *share,
+			     const struct path *path);
+int get_nlink(struct kstat *st);
+void ksmbd_conv_path_to_unix(char *path);
+void ksmbd_strip_last_slash(char *path);
+void ksmbd_conv_path_to_windows(char *path);
+char *ksmbd_casefold_sharename(struct unicode_map *um, const char *name);
+char *ksmbd_extract_sharename(struct unicode_map *um, const char *treename);
+
+#define KSMBD_DIR_INFO_ALIGNMENT	8
+struct ksmbd_dir_info;
+char *ksmbd_convert_dir_info_name(struct ksmbd_dir_info *d_info,
+				  const struct nls_table *local_nls,
+				  int *conv_len);
+
+#define NTFS_TIME_OFFSET	((u64)(369 * 365 + 89) * 24 * 3600 * 10000000)
+struct timespec64 ksmbd_NTtimeToUnix(__le64 ntutc);
+u64 ksmbd_UnixTimeToNT(struct timespec64 t);
+long long ksmbd_systime(void);
+
+#ifdef CONFIG_PROC_FS
+struct ksmbd_const_name {
+	unsigned int const_value;
+	const char *name;
+};
+
+int ksmbd_proc_init(void);
+void ksmbd_proc_cleanup(void);
+void ksmbd_proc_reset(void);
+struct proc_dir_entry *ksmbd_proc_create(const char *name,
+					 int (*show)(struct seq_file *m, void *v),
+			     void *v);
+void ksmbd_proc_show_flag_names(struct seq_file *m,
+				const struct ksmbd_const_name *table,
+				int count,
+				unsigned int flags);
+const char *ksmbd_proc_const_name(const struct ksmbd_const_name *table,
+				  int count, unsigned int const_value);
+#else
+static inline int ksmbd_proc_init(void) { return 0; }
+static inline void ksmbd_proc_cleanup(void) {}
+static inline void ksmbd_proc_reset(void) {}
+#endif
+#endif /* __KSMBD_MISC_H__ */