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>

3 files changed, 81 insertions, 0 deletions

diff --git a/drivers/reset/tegra/Kconfig b/drivers/reset/tegra/Kconfig
new file mode 100644
index 000000000..4a2d26d12
--- /dev/null
+++ b/drivers/reset/tegra/Kconfig
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config RESET_TEGRA_BPMP
+	bool "Tegra BPMP Reset Driver" if COMPILE_TEST
+	default TEGRA_BPMP
diff --git a/drivers/reset/tegra/Makefile b/drivers/reset/tegra/Makefile
new file mode 100644
index 000000000..eccba896a
--- /dev/null
+++ b/drivers/reset/tegra/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_RESET_TEGRA_BPMP) += reset-bpmp.o
diff --git a/drivers/reset/tegra/reset-bpmp.c b/drivers/reset/tegra/reset-bpmp.c
new file mode 100644
index 000000000..4c5bba52b
--- /dev/null
+++ b/drivers/reset/tegra/reset-bpmp.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 NVIDIA Corporation
+ */
+
+#include <linux/reset-controller.h>
+
+#include <soc/tegra/bpmp.h>
+#include <soc/tegra/bpmp-abi.h>
+
+static struct tegra_bpmp *to_tegra_bpmp(struct reset_controller_dev *rstc)
+{
+	return container_of(rstc, struct tegra_bpmp, rstc);
+}
+
+static int tegra_bpmp_reset_common(struct reset_controller_dev *rstc,
+				   enum mrq_reset_commands command,
+				   unsigned int id)
+{
+	struct tegra_bpmp *bpmp = to_tegra_bpmp(rstc);
+	struct mrq_reset_request request;
+	struct tegra_bpmp_message msg;
+	int err;
+
+	memset(&request, 0, sizeof(request));
+	request.cmd = command;
+	request.reset_id = id;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_RESET;
+	msg.tx.data = &request;
+	msg.tx.size = sizeof(request);
+
+	err = tegra_bpmp_transfer(bpmp, &msg);
+	if (err)
+		return err;
+	if (msg.rx.ret)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int tegra_bpmp_reset_module(struct reset_controller_dev *rstc,
+				   unsigned long id)
+{
+	return tegra_bpmp_reset_common(rstc, CMD_RESET_MODULE, id);
+}
+
+static int tegra_bpmp_reset_assert(struct reset_controller_dev *rstc,
+				   unsigned long id)
+{
+	return tegra_bpmp_reset_common(rstc, CMD_RESET_ASSERT, id);
+}
+
+static int tegra_bpmp_reset_deassert(struct reset_controller_dev *rstc,
+				     unsigned long id)
+{
+	return tegra_bpmp_reset_common(rstc, CMD_RESET_DEASSERT, id);
+}
+
+static const struct reset_control_ops tegra_bpmp_reset_ops = {
+	.reset = tegra_bpmp_reset_module,
+	.assert = tegra_bpmp_reset_assert,
+	.deassert = tegra_bpmp_reset_deassert,
+};
+
+int tegra_bpmp_init_resets(struct tegra_bpmp *bpmp)
+{
+	bpmp->rstc.ops = &tegra_bpmp_reset_ops;
+	bpmp->rstc.owner = THIS_MODULE;
+	bpmp->rstc.of_node = bpmp->dev->of_node;
+	bpmp->rstc.nr_resets = bpmp->soc->num_resets;
+
+	return devm_reset_controller_register(bpmp->dev, &bpmp->rstc);
+}