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, 307 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/utbuffer.c b/drivers/acpi/acpica/utbuffer.c
new file mode 100644
index 000000000..4193ceb93
--- /dev/null
+++ b/drivers/acpi/acpica/utbuffer.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: utbuffer - Buffer dump routines
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+
+#define _COMPONENT          ACPI_UTILITIES
+ACPI_MODULE_NAME("utbuffer")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_dump_buffer
+ *
+ * PARAMETERS:  buffer              - Buffer to dump
+ *              count               - Amount to dump, in bytes
+ *              display             - BYTE, WORD, DWORD, or QWORD display:
+ *                                      DB_BYTE_DISPLAY
+ *                                      DB_WORD_DISPLAY
+ *                                      DB_DWORD_DISPLAY
+ *                                      DB_QWORD_DISPLAY
+ *              base_offset         - Beginning buffer offset (display only)
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Generic dump buffer in both hex and ascii.
+ *
+ ******************************************************************************/
+void acpi_ut_dump_buffer(u8 *buffer, u32 count, u32 display, u32 base_offset)
+{
+	u32 i = 0;
+	u32 j;
+	u32 temp32;
+	u8 buf_char;
+	u32 display_data_only = display & DB_DISPLAY_DATA_ONLY;
+
+	display &= ~DB_DISPLAY_DATA_ONLY;
+	if (!buffer) {
+		acpi_os_printf("Null Buffer Pointer in DumpBuffer!\n");
+		return;
+	}
+
+	if ((count < 4) || (count & 0x01)) {
+		display = DB_BYTE_DISPLAY;
+	}
+
+	/* Nasty little dump buffer routine! */
+
+	while (i < count) {
+
+		/* Print current offset */
+
+		if (!display_data_only) {
+			acpi_os_printf("%8.4X: ", (base_offset + i));
+		}
+
+		/* Print 16 hex chars */
+
+		for (j = 0; j < 16;) {
+			if (i + j >= count) {
+
+				/* Dump fill spaces */
+
+				acpi_os_printf("%*s", ((display * 2) + 1), " ");
+				j += display;
+				continue;
+			}
+
+			switch (display) {
+			case DB_BYTE_DISPLAY:
+			default:	/* Default is BYTE display */
+
+				acpi_os_printf("%02X ",
+					       buffer[(acpi_size)i + j]);
+				break;
+
+			case DB_WORD_DISPLAY:
+
+				ACPI_MOVE_16_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				acpi_os_printf("%04X ", temp32);
+				break;
+
+			case DB_DWORD_DISPLAY:
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				acpi_os_printf("%08X ", temp32);
+				break;
+
+			case DB_QWORD_DISPLAY:
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				acpi_os_printf("%08X", temp32);
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j +
+							   4]);
+				acpi_os_printf("%08X ", temp32);
+				break;
+			}
+
+			j += display;
+		}
+
+		/*
+		 * Print the ASCII equivalent characters but watch out for the bad
+		 * unprintable ones (printable chars are 0x20 through 0x7E)
+		 */
+		if (!display_data_only) {
+			acpi_os_printf(" ");
+			for (j = 0; j < 16; j++) {
+				if (i + j >= count) {
+					acpi_os_printf("\n");
+					return;
+				}
+
+				/*
+				 * Add comment characters so rest of line is ignored when
+				 * compiled
+				 */
+				if (j == 0) {
+					acpi_os_printf("// ");
+				}
+
+				buf_char = buffer[(acpi_size)i + j];
+				if (isprint(buf_char)) {
+					acpi_os_printf("%c", buf_char);
+				} else {
+					acpi_os_printf(".");
+				}
+			}
+
+			/* Done with that line. */
+
+			acpi_os_printf("\n");
+		}
+		i += 16;
+	}
+
+	return;
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_debug_dump_buffer
+ *
+ * PARAMETERS:  buffer              - Buffer to dump
+ *              count               - Amount to dump, in bytes
+ *              display             - BYTE, WORD, DWORD, or QWORD display:
+ *                                      DB_BYTE_DISPLAY
+ *                                      DB_WORD_DISPLAY
+ *                                      DB_DWORD_DISPLAY
+ *                                      DB_QWORD_DISPLAY
+ *              component_ID        - Caller's component ID
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Generic dump buffer in both hex and ascii.
+ *
+ ******************************************************************************/
+
+void
+acpi_ut_debug_dump_buffer(u8 *buffer, u32 count, u32 display, u32 component_id)
+{
+
+	/* Only dump the buffer if tracing is enabled */
+
+	if (!((ACPI_LV_TABLES & acpi_dbg_level) &&
+	      (component_id & acpi_dbg_layer))) {
+		return;
+	}
+
+	acpi_ut_dump_buffer(buffer, count, display, 0);
+}
+
+#ifdef ACPI_APPLICATION
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_dump_buffer_to_file
+ *
+ * PARAMETERS:  file                - File descriptor
+ *              buffer              - Buffer to dump
+ *              count               - Amount to dump, in bytes
+ *              display             - BYTE, WORD, DWORD, or QWORD display:
+ *                                      DB_BYTE_DISPLAY
+ *                                      DB_WORD_DISPLAY
+ *                                      DB_DWORD_DISPLAY
+ *                                      DB_QWORD_DISPLAY
+ *              base_offset         - Beginning buffer offset (display only)
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Generic dump buffer in both hex and ascii to a file.
+ *
+ ******************************************************************************/
+
+void
+acpi_ut_dump_buffer_to_file(ACPI_FILE file,
+			    u8 *buffer, u32 count, u32 display, u32 base_offset)
+{
+	u32 i = 0;
+	u32 j;
+	u32 temp32;
+	u8 buf_char;
+
+	if (!buffer) {
+		fprintf(file, "Null Buffer Pointer in DumpBuffer!\n");
+		return;
+	}
+
+	if ((count < 4) || (count & 0x01)) {
+		display = DB_BYTE_DISPLAY;
+	}
+
+	/* Nasty little dump buffer routine! */
+
+	while (i < count) {
+
+		/* Print current offset */
+
+		fprintf(file, "%8.4X: ", (base_offset + i));
+
+		/* Print 16 hex chars */
+
+		for (j = 0; j < 16;) {
+			if (i + j >= count) {
+
+				/* Dump fill spaces */
+
+				fprintf(file, "%*s", ((display * 2) + 1), " ");
+				j += display;
+				continue;
+			}
+
+			switch (display) {
+			case DB_BYTE_DISPLAY:
+			default:	/* Default is BYTE display */
+
+				fprintf(file, "%02X ",
+					buffer[(acpi_size)i + j]);
+				break;
+
+			case DB_WORD_DISPLAY:
+
+				ACPI_MOVE_16_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				fprintf(file, "%04X ", temp32);
+				break;
+
+			case DB_DWORD_DISPLAY:
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				fprintf(file, "%08X ", temp32);
+				break;
+
+			case DB_QWORD_DISPLAY:
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j]);
+				fprintf(file, "%08X", temp32);
+
+				ACPI_MOVE_32_TO_32(&temp32,
+						   &buffer[(acpi_size)i + j +
+							   4]);
+				fprintf(file, "%08X ", temp32);
+				break;
+			}
+
+			j += display;
+		}
+
+		/*
+		 * Print the ASCII equivalent characters but watch out for the bad
+		 * unprintable ones (printable chars are 0x20 through 0x7E)
+		 */
+		fprintf(file, " ");
+		for (j = 0; j < 16; j++) {
+			if (i + j >= count) {
+				fprintf(file, "\n");
+				return;
+			}
+
+			buf_char = buffer[(acpi_size)i + j];
+			if (isprint(buf_char)) {
+				fprintf(file, "%c", buf_char);
+			} else {
+				fprintf(file, ".");
+			}
+		}
+
+		/* Done with that line. */
+
+		fprintf(file, "\n");
+		i += 16;
+	}
+
+	return;
+}
+#endif