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, 36 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/Kbuild b/include/uapi/asm-generic/Kbuild
new file mode 100644
index 000000000..ebb180aac
--- /dev/null
+++ b/include/uapi/asm-generic/Kbuild
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Headers that are mandatory in usr/include/asm/
+# (This file is not included when SRCARCH=um since UML does not support UAPI.)
+
+mandatory-y += auxvec.h
+mandatory-y += bitsperlong.h
+mandatory-y += bpf_perf_event.h
+mandatory-y += byteorder.h
+mandatory-y += errno.h
+mandatory-y += fcntl.h
+mandatory-y += ioctl.h
+mandatory-y += ioctls.h
+mandatory-y += ipcbuf.h
+mandatory-y += mman.h
+mandatory-y += msgbuf.h
+mandatory-y += param.h
+mandatory-y += poll.h
+mandatory-y += posix_types.h
+mandatory-y += ptrace.h
+mandatory-y += resource.h
+mandatory-y += sembuf.h
+mandatory-y += setup.h
+mandatory-y += shmbuf.h
+mandatory-y += sigcontext.h
+mandatory-y += siginfo.h
+mandatory-y += signal.h
+mandatory-y += socket.h
+mandatory-y += sockios.h
+mandatory-y += stat.h
+mandatory-y += statfs.h
+mandatory-y += swab.h
+mandatory-y += termbits.h
+mandatory-y += termios.h
+mandatory-y += types.h
+mandatory-y += unistd.h