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, 84 insertions, 0 deletions

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
new file mode 100644
index 000000000..d3795860f
--- /dev/null
+++ b/drivers/rpmsg/Kconfig
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "Rpmsg drivers"
+
+# RPMSG always gets selected by whoever wants it
+config RPMSG
+	tristate
+
+config RPMSG_CHAR
+	tristate "RPMSG device interface"
+	depends on RPMSG
+	depends on NET
+	help
+	  Say Y here to export rpmsg endpoints as device files, usually found
+	  in /dev. They make it possible for user-space programs to send and
+	  receive rpmsg packets.
+
+config RPMSG_CTRL
+	tristate "RPMSG control interface"
+	depends on RPMSG && ( RPMSG_CHAR || RPMSG_CHAR=n )
+	help
+	  Say Y here to enable the support of the /dev/rpmsg_ctrlX API. This API
+	  allows user-space programs to create endpoints with specific service name,
+	  source and destination addresses.
+
+config RPMSG_NS
+	tristate "RPMSG name service announcement"
+	depends on RPMSG
+	help
+	  Say Y here to enable the support of the name service announcement
+	  channel that probes the associated RPMsg device on remote endpoint
+	  service announcement.
+
+config RPMSG_MTK_SCP
+	tristate "MediaTek SCP"
+	depends on MTK_SCP
+	select RPMSG
+	help
+	  Say y here to enable support providing communication channels to
+	  remote processors in MediaTek platforms.
+	  This use IPI and IPC to communicate with remote processors.
+
+config RPMSG_QCOM_GLINK
+	tristate
+	select RPMSG
+
+config RPMSG_QCOM_GLINK_RPM
+	tristate "Qualcomm RPM Glink driver"
+	select RPMSG_QCOM_GLINK
+	depends on HAS_IOMEM
+	depends on MAILBOX
+	help
+	  Say y here to enable support for the GLINK RPM communication driver,
+	  which serves as a channel for communication with the RPM in GLINK
+	  enabled systems.
+
+config RPMSG_QCOM_GLINK_SMEM
+	tristate "Qualcomm SMEM Glink driver"
+	select RPMSG_QCOM_GLINK
+	depends on MAILBOX
+	depends on QCOM_SMEM
+	help
+	  Say y here to enable support for the GLINK SMEM communication driver,
+	  which provides support for using the GLINK communication protocol
+	  over SMEM.
+
+config RPMSG_QCOM_SMD
+	tristate "Qualcomm Shared Memory Driver (SMD)"
+	depends on MAILBOX
+	depends on QCOM_SMEM
+	select RPMSG
+	help
+	  Say y here to enable support for the Qualcomm Shared Memory Driver
+	  providing communication channels to remote processors in Qualcomm
+	  platforms.
+
+config RPMSG_VIRTIO
+	tristate "Virtio RPMSG bus driver"
+	depends on HAS_DMA
+	select RPMSG
+	select RPMSG_NS
+	select VIRTIO
+
+endmenu