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, 41 insertions, 0 deletions

diff --git a/lib/raid/raid6/algos.h b/lib/raid/raid6/algos.h
new file mode 100644
index 000000000..43f636be1
--- /dev/null
+++ b/lib/raid/raid6/algos.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright 2003 H. Peter Anvin - All Rights Reserved
+ */
+#ifndef _PQ_IMPL_H
+#define _PQ_IMPL_H
+
+#include <linux/init.h>
+#include <linux/raid/pq_tables.h>
+
+/* Routine choices */
+struct raid6_calls {
+	const char *name;
+	void (*gen_syndrome)(int disks, size_t bytes, void **ptrs);
+	void (*xor_syndrome)(int disks, int start, int stop, size_t bytes,
+			void **ptrs);
+};
+
+struct raid6_recov_calls {
+	const char *name;
+	void (*data2)(int disks, size_t bytes, int faila, int failb,
+			void **ptrs);
+	void (*datap)(int disks, size_t bytes, int faila, void **ptrs);
+};
+
+void __init raid6_algo_add(const struct raid6_calls *algo);
+void __init raid6_algo_add_default(void);
+void __init raid6_recov_algo_add(const struct raid6_recov_calls *algo);
+
+/* for the kunit test */
+const struct raid6_calls *raid6_algo_find(unsigned int idx);
+const struct raid6_recov_calls *raid6_recov_algo_find(unsigned int idx);
+
+/* generic implementations */
+extern const struct raid6_calls raid6_intx1;
+extern const struct raid6_calls raid6_intx2;
+extern const struct raid6_calls raid6_intx4;
+extern const struct raid6_calls raid6_intx8;
+extern const struct raid6_recov_calls raid6_recov_intx1;
+
+#endif /* _PQ_IMPL_H */