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, 71 insertions, 0 deletions

diff --git a/tools/perf/util/counts.c b/tools/perf/util/counts.c
new file mode 100644
index 000000000..11cd85b27
--- /dev/null
+++ b/tools/perf/util/counts.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "evsel.h"
+#include "counts.h"
+#include <perf/threadmap.h>
+#include <linux/zalloc.h>
+
+struct perf_counts *perf_counts__new(int ncpus, int nthreads)
+{
+	struct perf_counts *counts = zalloc(sizeof(*counts));
+
+	if (counts) {
+		struct xyarray *values;
+
+		values = xyarray__new(ncpus, nthreads, sizeof(struct perf_counts_values));
+		if (!values) {
+			free(counts);
+			return NULL;
+		}
+
+		counts->values = values;
+
+		values = xyarray__new(ncpus, nthreads, sizeof(bool));
+		if (!values) {
+			xyarray__delete(counts->values);
+			free(counts);
+			return NULL;
+		}
+
+		counts->loaded = values;
+	}
+
+	return counts;
+}
+
+void perf_counts__delete(struct perf_counts *counts)
+{
+	if (counts) {
+		xyarray__delete(counts->loaded);
+		xyarray__delete(counts->values);
+		free(counts);
+	}
+}
+
+void perf_counts__reset(struct perf_counts *counts)
+{
+	xyarray__reset(counts->loaded);
+	xyarray__reset(counts->values);
+}
+
+void evsel__reset_counts(struct evsel *evsel)
+{
+	perf_counts__reset(evsel->counts);
+}
+
+int evsel__alloc_counts(struct evsel *evsel)
+{
+	struct perf_cpu_map *cpus = evsel__cpus(evsel);
+	int nthreads = perf_thread_map__nr(evsel->core.threads);
+
+	evsel->counts = perf_counts__new(perf_cpu_map__nr(cpus), nthreads);
+	return evsel->counts != NULL ? 0 : -ENOMEM;
+}
+
+void evsel__free_counts(struct evsel *evsel)
+{
+	perf_counts__delete(evsel->counts);
+	evsel->counts = NULL;
+}