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, 66 insertions, 0 deletions

diff --git a/include/trace/events/siox.h b/include/trace/events/siox.h
new file mode 100644
index 000000000..68a43fc2c
--- /dev/null
+++ b/include/trace/events/siox.h
@@ -0,0 +1,66 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM siox
+
+#if !defined(_TRACE_SIOX_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SIOX_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(siox_set_data,
+	    TP_PROTO(const struct siox_master *smaster,
+		     const struct siox_device *sdevice,
+		     unsigned int devno, size_t bufoffset),
+	    TP_ARGS(smaster, sdevice, devno, bufoffset),
+	    TP_STRUCT__entry(
+			     __field(int, busno)
+			     __field(unsigned int, devno)
+			     __field(size_t, inbytes)
+			     __dynamic_array(u8, buf, sdevice->inbytes)
+			    ),
+	    TP_fast_assign(
+			   __entry->busno = smaster->busno;
+			   __entry->devno = devno;
+			   __entry->inbytes = sdevice->inbytes;
+			   memcpy(__get_dynamic_array(buf),
+				  smaster->buf + bufoffset, sdevice->inbytes);
+			  ),
+	    TP_printk("siox-%d-%u [%*phD]",
+		      __entry->busno,
+		      __entry->devno,
+		      (int)__entry->inbytes, __get_dynamic_array(buf)
+		     )
+);
+
+TRACE_EVENT(siox_get_data,
+	    TP_PROTO(const struct siox_master *smaster,
+		     const struct siox_device *sdevice,
+		     unsigned int devno, u8 status_clean,
+		     size_t bufoffset),
+	    TP_ARGS(smaster, sdevice, devno, status_clean, bufoffset),
+	    TP_STRUCT__entry(
+			     __field(int, busno)
+			     __field(unsigned int, devno)
+			     __field(u8, status_clean)
+			     __field(size_t, outbytes)
+			     __dynamic_array(u8, buf, sdevice->outbytes)
+			    ),
+	    TP_fast_assign(
+			   __entry->busno = smaster->busno;
+			   __entry->devno = devno;
+			   __entry->status_clean = status_clean;
+			   __entry->outbytes = sdevice->outbytes;
+			   memcpy(__get_dynamic_array(buf),
+				  smaster->buf + bufoffset, sdevice->outbytes);
+			  ),
+	    TP_printk("siox-%d-%u (%02hhx) [%*phD]",
+		      __entry->busno,
+		      __entry->devno,
+		      __entry->status_clean,
+		      (int)__entry->outbytes, __get_dynamic_array(buf)
+		     )
+);
+
+#endif /* if !defined(_TRACE_SIOX_H) || defined(TRACE_HEADER_MULTI_READ) */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>