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, 67 insertions, 0 deletions

diff --git a/fs/fuse/args.h b/fs/fuse/args.h
new file mode 100644
index 000000000..5173264a1
--- /dev/null
+++ b/fs/fuse/args.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _FS_FUSE_ARGS_H
+#define _FS_FUSE_ARGS_H
+
+#include <linux/types.h>
+
+struct fuse_mount;
+
+/** One input argument of a request */
+struct fuse_in_arg {
+	unsigned size;
+	const void *value;
+};
+
+/** One output argument of a request */
+struct fuse_arg {
+	unsigned size;
+	void *value;
+};
+
+struct fuse_args {
+	u64 nodeid;
+	u32 opcode;
+	u32 uid;
+	u32 gid;
+	u32 pid;
+	u8 in_numargs;
+	u8 out_numargs;
+	u8 ext_idx;
+	bool force:1;
+	bool noreply:1;
+	bool nocreds:1;
+	bool in_pages:1;
+	bool out_pages:1;
+	bool user_pages:1;
+	bool out_argvar:1;
+	bool page_zeroing:1;
+	bool page_replace:1;
+	bool may_block:1;
+	bool is_ext:1;
+	bool is_pinned:1;
+	bool invalidate_vmap:1;
+	bool abort_on_kill:1;
+	/* server requested io-uring zero-copy for this op */
+	bool zero_copy:1;
+	struct fuse_in_arg in_args[4];
+	struct fuse_arg out_args[2];
+	void (*end)(struct fuse_args *args, int error);
+	/* Used for kvec iter backed by vmalloc address */
+	void *vmap_base;
+};
+
+/** FUSE folio descriptor */
+struct fuse_folio_desc {
+	unsigned int length;
+	unsigned int offset;
+};
+
+struct fuse_args_pages {
+	struct fuse_args args;
+	struct folio **folios;
+	struct fuse_folio_desc *descs;
+	unsigned int num_folios;
+};
+
+#endif /* _FS_FUSE_ARGS_H */