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, 46 insertions, 0 deletions

diff --git a/include/hyperv/hvgdk_ext.h b/include/hyperv/hvgdk_ext.h
new file mode 100644
index 000000000..641b591ee
--- /dev/null
+++ b/include/hyperv/hvgdk_ext.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Type definitions for the Microsoft Hypervisor.
+ */
+#ifndef _HV_HVGDK_EXT_H
+#define _HV_HVGDK_EXT_H
+
+#include "hvgdk_mini.h"
+
+/* Extended hypercalls */
+#define HV_EXT_CALL_QUERY_CAPABILITIES		0x8001
+#define HV_EXT_CALL_MEMORY_HEAT_HINT		0x8003
+
+/* Extended hypercalls */
+enum {		/* HV_EXT_CALL */
+	HV_EXTCALL_QUERY_CAPABILITIES = 0x8001,
+	HV_EXTCALL_MEMORY_HEAT_HINT   = 0x8003,
+};
+
+/* HV_EXT_OUTPUT_QUERY_CAPABILITIES */
+#define HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT BIT(8)
+
+enum {		/* HV_EXT_MEMORY_HEAT_HINT_TYPE */
+	HV_EXTMEM_HEAT_HINT_COLD = 0,
+	HV_EXTMEM_HEAT_HINT_HOT = 1,
+	HV_EXTMEM_HEAT_HINT_COLD_DISCARD = 2,
+	HV_EXTMEM_HEAT_HINT_MAX
+};
+
+/*
+ * The whole argument should fit in a page to be able to pass to the hypervisor
+ * in one hypercall.
+ */
+#define HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES  \
+	((HV_HYP_PAGE_SIZE - sizeof(struct hv_memory_hint)) / \
+		sizeof(union hv_gpa_page_range))
+
+/* HvExtCallMemoryHeatHint hypercall */
+#define HV_EXT_MEMORY_HEAT_HINT_TYPE_COLD_DISCARD	2
+struct hv_memory_hint {		/* HV_EXT_INPUT_MEMORY_HEAT_HINT */
+	u64 heat_type : 2;	/* HV_EXTMEM_HEAT_HINT_* */
+	u64 reserved : 62;
+	union hv_gpa_page_range ranges[];
+} __packed;
+
+#endif /* _HV_HVGDK_EXT_H */