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, 25 insertions, 0 deletions

diff --git a/arch/alpha/boot/bootloader.lds b/arch/alpha/boot/bootloader.lds
new file mode 100644
index 000000000..8cdff54c6
--- /dev/null
+++ b/arch/alpha/boot/bootloader.lds
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+OUTPUT_FORMAT("elf64-alpha")
+ENTRY(__start)
+printk = srm_printk;
+SECTIONS
+{
+  . = 0x20000000;
+  .text : { *(.text) }
+  _etext = .;
+  PROVIDE (etext = .);
+  .rodata : { *(.rodata) *(.rodata.*) }
+  .data : { *(.data) CONSTRUCTORS }
+  .got : { *(.got) }
+  .sdata : { *(.sdata) }
+  _edata = .;
+  PROVIDE (edata = .);
+  .sbss : { *(.sbss) *(.scommon) }
+  .bss : { *(.bss) *(COMMON) }
+  _end = . ;
+  PROVIDE (end = .);
+
+  .mdebug 0 : { *(.mdebug) }
+  .note 0 : { *(.note) }
+  .comment 0 : { *(.comment) }
+}