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, 69 insertions, 0 deletions

diff --git a/include/trace/events/vb2.h b/include/trace/events/vb2.h
new file mode 100644
index 000000000..a40146dea
--- /dev/null
+++ b/include/trace/events/vb2.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vb2
+
+#if !defined(_TRACE_VB2_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_VB2_H
+
+#include <linux/tracepoint.h>
+#include <media/videobuf2-core.h>
+
+DECLARE_EVENT_CLASS(vb2_event_class,
+	TP_PROTO(struct vb2_queue *q, struct vb2_buffer *vb),
+	TP_ARGS(q, vb),
+
+	TP_STRUCT__entry(
+		__field(void *, owner)
+		__field(u32, queued_count)
+		__field(int, owned_by_drv_count)
+		__field(u32, index)
+		__field(u32, type)
+		__field(u32, bytesused)
+		__field(u64, timestamp)
+	),
+
+	TP_fast_assign(
+		__entry->owner = q->owner;
+		__entry->queued_count = q->queued_count;
+		__entry->owned_by_drv_count =
+			atomic_read(&q->owned_by_drv_count);
+		__entry->index = vb->index;
+		__entry->type = vb->type;
+		__entry->bytesused = vb->planes[0].bytesused;
+		__entry->timestamp = vb->timestamp;
+	),
+
+	TP_printk("owner = %p, queued = %u, owned_by_drv = %d, index = %u, "
+		  "type = %u, bytesused = %u, timestamp = %llu", __entry->owner,
+		  __entry->queued_count,
+		  __entry->owned_by_drv_count,
+		  __entry->index, __entry->type,
+		  __entry->bytesused,
+		  __entry->timestamp
+	)
+)
+
+DEFINE_EVENT(vb2_event_class, vb2_buf_done,
+	TP_PROTO(struct vb2_queue *q, struct vb2_buffer *vb),
+	TP_ARGS(q, vb)
+);
+
+DEFINE_EVENT(vb2_event_class, vb2_buf_queue,
+	TP_PROTO(struct vb2_queue *q, struct vb2_buffer *vb),
+	TP_ARGS(q, vb)
+);
+
+DEFINE_EVENT(vb2_event_class, vb2_dqbuf,
+	TP_PROTO(struct vb2_queue *q, struct vb2_buffer *vb),
+	TP_ARGS(q, vb)
+);
+
+DEFINE_EVENT(vb2_event_class, vb2_qbuf,
+	TP_PROTO(struct vb2_queue *q, struct vb2_buffer *vb),
+	TP_ARGS(q, vb)
+);
+
+#endif /* if !defined(_TRACE_VB2_H) || defined(TRACE_HEADER_MULTI_READ) */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>