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, 77 insertions, 0 deletions

diff --git a/net/mac80211/trace.c b/net/mac80211/trace.c
new file mode 100644
index 000000000..837857261
--- /dev/null
+++ b/net/mac80211/trace.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+/* bug in tracepoint.h, it should include this */
+#include <linux/module.h>
+
+/* sparse isn't too happy with all macros... */
+#ifndef __CHECKER__
+#include <net/cfg80211.h>
+#include "driver-ops.h"
+#include "debug.h"
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+#include "trace_msg.h"
+
+#ifdef CONFIG_MAC80211_MESSAGE_TRACING
+void __sdata_info(const char *fmt, ...)
+{
+	struct va_format vaf = {
+		.fmt = fmt,
+	};
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.va = &args;
+
+	pr_info("%pV", &vaf);
+	trace_mac80211_info(&vaf);
+	va_end(args);
+}
+
+void __sdata_dbg(bool print, const char *fmt, ...)
+{
+	struct va_format vaf = {
+		.fmt = fmt,
+	};
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.va = &args;
+
+	if (print)
+		pr_debug("%pV", &vaf);
+	trace_mac80211_dbg(&vaf);
+	va_end(args);
+}
+
+void __sdata_err(const char *fmt, ...)
+{
+	struct va_format vaf = {
+		.fmt = fmt,
+	};
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.va = &args;
+
+	pr_err("%pV", &vaf);
+	trace_mac80211_err(&vaf);
+	va_end(args);
+}
+
+void __wiphy_dbg(struct wiphy *wiphy, bool print, const char *fmt, ...)
+{
+	struct va_format vaf = {
+		.fmt = fmt,
+	};
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.va = &args;
+
+	if (print)
+		wiphy_dbg(wiphy, "%pV", &vaf);
+	trace_mac80211_dbg(&vaf);
+	va_end(args);
+}
+#endif
+#endif