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>

4 files changed, 143 insertions, 0 deletions

diff --git a/tools/testing/rbtree/Makefile b/tools/testing/rbtree/Makefile
new file mode 100644
index 000000000..d7bbae2af
--- /dev/null
+++ b/tools/testing/rbtree/Makefile
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0
+
+.PHONY: clean
+
+TARGETS = rbtree_test interval_tree_test
+OFILES = $(SHARED_OFILES) rbtree-shim.o interval_tree-shim.o maple-shim.o
+DEPS = ../../../include/linux/rbtree.h \
+	../../../include/linux/rbtree_types.h \
+	../../../include/linux/rbtree_augmented.h \
+	../../../include/linux/interval_tree.h \
+	../../../include/linux/interval_tree_generic.h \
+	../../../lib/rbtree.c \
+	../../../lib/interval_tree.c
+
+targets: $(TARGETS)
+
+include ../shared/shared.mk
+
+ifeq ($(DEBUG), 1)
+	CFLAGS += -g
+endif
+
+$(TARGETS):	$(OFILES)
+
+rbtree-shim.o: $(DEPS)
+rbtree_test.o:  ../../../lib/rbtree_test.c
+interval_tree-shim.o: $(DEPS)
+interval_tree-shim.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+interval_tree_test.o: 	../../../lib/interval_tree_test.c
+interval_tree_test.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/*
diff --git a/tools/testing/rbtree/interval_tree_test.c b/tools/testing/rbtree/interval_tree_test.c
new file mode 100644
index 000000000..49bc5b534
--- /dev/null
+++ b/tools/testing/rbtree/interval_tree_test.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * interval_tree.c: Userspace Interval Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+#include "maple-shared.h"
+
+#include "../../../lib/interval_tree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland interval tree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the interval tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the tree\n");
+	fprintf(stderr, "  -q: Number of searches to the interval tree\n");
+	fprintf(stderr, "  -s: Number of iterations searching the tree\n");
+	fprintf(stderr, "  -a: Searches will iterate all nodes in the tree\n");
+	fprintf(stderr, "  -m: Largest value for the interval's endpoint\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void interval_tree_tests(void)
+{
+	interval_tree_test_init();
+	interval_tree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:q:s:am:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'q')
+			nsearches = strtoul(optarg, NULL, 0);
+		else if (opt == 's')
+			search_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'a')
+			search_all = true;
+		else if (opt == 'm')
+			max_endpoint = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	maple_tree_init();
+	interval_tree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/rbtree_test.c b/tools/testing/rbtree/rbtree_test.c
new file mode 100644
index 000000000..585c970f6
--- /dev/null
+++ b/tools/testing/rbtree/rbtree_test.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rbtree_test.c: Userspace Red Black Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/init.h>
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+
+#include "../../../lib/rbtree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland rbtree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the rb-tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the rb-tree\n");
+	fprintf(stderr, "  -c: Number of iterations modifying and verifying the rb-tree\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void rbtree_tests(void)
+{
+	rbtree_test_init();
+	rbtree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:c:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'c')
+			check_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	rbtree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/test.h b/tools/testing/rbtree/test.h
new file mode 100644
index 000000000..f1f1b545b
--- /dev/null
+++ b/tools/testing/rbtree/test.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+void rbtree_tests(void);
+void interval_tree_tests(void);