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, 59 insertions, 0 deletions

diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
new file mode 100644
index 000000000..a714cc2bf
--- /dev/null
+++ b/rust/helpers/pci.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+
+__rust_helper u16 rust_helper_pci_dev_id(struct pci_dev *dev)
+{
+	return PCI_DEVID(dev->bus->number, dev->devfn);
+}
+
+__rust_helper resource_size_t
+rust_helper_pci_resource_start(struct pci_dev *pdev, int bar)
+{
+	return pci_resource_start(pdev, bar);
+}
+
+__rust_helper resource_size_t rust_helper_pci_resource_len(struct pci_dev *pdev,
+							   int bar)
+{
+	return pci_resource_len(pdev, bar);
+}
+
+__rust_helper bool rust_helper_dev_is_pci(const struct device *dev)
+{
+	return dev_is_pci(dev);
+}
+
+__rust_helper unsigned int rust_helper_pci_irq_type(struct pci_dev *pdev)
+{
+	return pci_irq_type(pdev);
+}
+
+#ifndef CONFIG_PCI_IOV
+__rust_helper unsigned int
+rust_helper_pci_sriov_get_totalvfs(struct pci_dev *pdev)
+{
+	return pci_sriov_get_totalvfs(pdev);
+}
+#endif
+
+#ifndef CONFIG_PCI_MSI
+__rust_helper int rust_helper_pci_alloc_irq_vectors(struct pci_dev *dev,
+						    unsigned int min_vecs,
+						    unsigned int max_vecs,
+						    unsigned int flags)
+{
+	return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
+}
+
+__rust_helper void rust_helper_pci_free_irq_vectors(struct pci_dev *dev)
+{
+	pci_free_irq_vectors(dev);
+}
+
+__rust_helper int rust_helper_pci_irq_vector(struct pci_dev *pdev,
+					     unsigned int nvec)
+{
+	return pci_irq_vector(pdev, nvec);
+}
+#endif