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, 70 insertions, 0 deletions

diff --git a/tools/perf/util/parse-sublevel-options.c b/tools/perf/util/parse-sublevel-options.c
new file mode 100644
index 000000000..a841d17ff
--- /dev/null
+++ b/tools/perf/util/parse-sublevel-options.c
@@ -0,0 +1,70 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "util/debug.h"
+#include "util/parse-sublevel-options.h"
+
+static int parse_one_sublevel_option(const char *str,
+				     struct sublevel_option *opts)
+{
+	struct sublevel_option *opt = opts;
+	char *vstr, *s = strdup(str);
+	int v = 1;
+
+	if (!s) {
+		pr_err("no memory\n");
+		return -1;
+	}
+
+	vstr = strchr(s, '=');
+	if (vstr)
+		*vstr++ = 0;
+
+	while (opt->name) {
+		if (!strcmp(s, opt->name))
+			break;
+		opt++;
+	}
+
+	if (!opt->name) {
+		pr_err("Unknown option name '%s'\n", s);
+		free(s);
+		return -1;
+	}
+
+	if (vstr)
+		v = atoi(vstr);
+
+	*opt->value_ptr = v;
+	free(s);
+	return 0;
+}
+
+/* parse options like --foo a=<n>,b,c... */
+int perf_parse_sublevel_options(const char *str, struct sublevel_option *opts)
+{
+	char *s = strdup(str);
+	char *p = NULL;
+	int ret;
+
+	if (!s) {
+		pr_err("no memory\n");
+		return -1;
+	}
+
+	p = strtok(s, ",");
+	while (p) {
+		ret = parse_one_sublevel_option(p, opts);
+		if (ret) {
+			free(s);
+			return ret;
+		}
+
+		p = strtok(NULL, ",");
+	}
+
+	free(s);
+	return 0;
+}