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, 63 insertions, 0 deletions

diff --git a/tools/perf/tests/mem.c b/tools/perf/tests/mem.c
new file mode 100644
index 000000000..cb3d749e1
--- /dev/null
+++ b/tools/perf/tests/mem.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "util/map_symbol.h"
+#include "util/mem-events.h"
+#include "util/mem-info.h"
+#include "util/symbol.h"
+#include "linux/perf_event.h"
+#include "util/debug.h"
+#include "tests.h"
+#include <string.h>
+
+static int check(union perf_mem_data_src data_src,
+		  const char *string)
+{
+	char out[100];
+	char failure[100];
+	struct mem_info *mi = mem_info__new();
+	int n;
+
+	TEST_ASSERT_VAL("Memory allocation failed", mi);
+	*mem_info__data_src(mi) = data_src;
+	n = perf_mem__snp_scnprintf(out, sizeof out, mi);
+	n += perf_mem__lvl_scnprintf(out + n, sizeof out - n, mi);
+	mem_info__put(mi);
+	scnprintf(failure, sizeof failure, "unexpected %s", out);
+	TEST_ASSERT_VAL(failure, !strcmp(string, out));
+	return 0;
+}
+
+static int test__mem(struct test_suite *text __maybe_unused, int subtest __maybe_unused)
+{
+	int ret = 0;
+	union perf_mem_data_src src;
+
+	memset(&src, 0, sizeof(src));
+
+	src.mem_lvl = PERF_MEM_LVL_HIT;
+	src.mem_lvl_num = 4;
+
+	ret |= check(src, "N/AL4 hit");
+
+	src.mem_remote = 1;
+
+	ret |= check(src, "N/ARemote L4 hit");
+
+	src.mem_lvl = PERF_MEM_LVL_MISS;
+	src.mem_lvl_num = PERF_MEM_LVLNUM_PMEM;
+	src.mem_remote = 0;
+
+	ret |= check(src, "N/APMEM miss");
+
+	src.mem_remote = 1;
+
+	ret |= check(src, "N/ARemote PMEM miss");
+
+	src.mem_snoopx = PERF_MEM_SNOOPX_FWD;
+	src.mem_lvl_num = PERF_MEM_LVLNUM_RAM;
+
+	ret |= check(src , "FwdRemote RAM miss");
+
+	return ret;
+}
+
+DEFINE_SUITE("Test data source output", mem);