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, 57 insertions, 0 deletions

diff --git a/rust/helpers/regulator.c b/rust/helpers/regulator.c
new file mode 100644
index 000000000..9ec5237f4
--- /dev/null
+++ b/rust/helpers/regulator.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/regulator/consumer.h>
+
+#ifndef CONFIG_REGULATOR
+
+__rust_helper void rust_helper_regulator_put(struct regulator *regulator)
+{
+	regulator_put(regulator);
+}
+
+__rust_helper int rust_helper_regulator_set_voltage(struct regulator *regulator,
+						    int min_uV, int max_uV)
+{
+	return regulator_set_voltage(regulator, min_uV, max_uV);
+}
+
+__rust_helper int rust_helper_regulator_get_voltage(struct regulator *regulator)
+{
+	return regulator_get_voltage(regulator);
+}
+
+__rust_helper struct regulator *rust_helper_regulator_get(struct device *dev,
+							  const char *id)
+{
+	return regulator_get(dev, id);
+}
+
+__rust_helper int rust_helper_regulator_enable(struct regulator *regulator)
+{
+	return regulator_enable(regulator);
+}
+
+__rust_helper int rust_helper_regulator_disable(struct regulator *regulator)
+{
+	return regulator_disable(regulator);
+}
+
+__rust_helper int rust_helper_regulator_is_enabled(struct regulator *regulator)
+{
+	return regulator_is_enabled(regulator);
+}
+
+__rust_helper int rust_helper_devm_regulator_get_enable(struct device *dev,
+							const char *id)
+{
+	return devm_regulator_get_enable(dev, id);
+}
+
+__rust_helper int
+rust_helper_devm_regulator_get_enable_optional(struct device *dev,
+					       const char *id)
+{
+	return devm_regulator_get_enable_optional(dev, id);
+}
+
+#endif