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, 32 insertions, 0 deletions

diff --git a/tools/perf/util/spark.c b/tools/perf/util/spark.c
new file mode 100644
index 000000000..65ca253cc
--- /dev/null
+++ b/tools/perf/util/spark.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "spark.h"
+#include <limits.h>
+#include <linux/kernel.h>
+
+#define SPARK_SHIFT 8
+
+/* Print spark lines on outf for numval values in val. */
+int print_spark(char *bf, int size, unsigned long *val, int numval)
+{
+	static const char *ticks[NUM_SPARKS] = {
+		"▁",  "▂", "▃", "▄", "▅", "▆", "▇", "█"
+	};
+	int i, printed = 0;
+	unsigned long min = ULONG_MAX, max = 0, f;
+
+	for (i = 0; i < numval; i++) {
+		if (val[i] < min)
+			min = val[i];
+		if (val[i] > max)
+			max = val[i];
+	}
+	f = ((max - min) << SPARK_SHIFT) / (NUM_SPARKS - 1);
+	if (f < 1)
+		f = 1;
+	for (i = 0; i < numval; i++) {
+		printed += scnprintf(bf + printed, size - printed, "%s",
+				     ticks[((val[i] - min) << SPARK_SHIFT) / f]);
+	}
+
+	return printed;
+}