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, 42 insertions, 0 deletions

diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
new file mode 100644
index 000000000..9295055cd
--- /dev/null
+++ b/arch/arm/lib/Makefile
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# linux/arch/arm/lib/Makefile
+#
+# Copyright (C) 1995-2000 Russell King
+#
+
+lib-y		:= changebit.o csumipv6.o csumpartial.o               \
+		   csumpartialcopy.o csumpartialcopyuser.o clearbit.o \
+		   delay.o delay-loop.o findbit.o memchr.o memcpy.o   \
+		   memmove.o memset.o setbit.o                        \
+		   strchr.o strrchr.o                                 \
+		   testchangebit.o testclearbit.o testsetbit.o        \
+		   ashldi3.o ashrdi3.o lshrdi3.o muldi3.o             \
+		   ucmpdi2.o lib1funcs.o div64.o                      \
+		   io-readsb.o io-writesb.o io-readsl.o io-writesl.o  \
+		   call_with_stack.o bswapsdi2.o
+
+mmu-y		:= clear_user.o copy_page.o getuser.o putuser.o       \
+		   copy_from_user.o copy_to_user.o
+
+ifdef CONFIG_CC_IS_CLANG
+  lib-y	+= backtrace-clang.o
+else
+  lib-y	+= backtrace.o
+endif
+
+# using lib_ here won't override already available weak symbols
+obj-$(CONFIG_UACCESS_WITH_MEMCPY) += uaccess_with_memcpy.o
+
+lib-$(CONFIG_MMU) += $(mmu-y)
+
+ifeq ($(CONFIG_CPU_32v3),y)
+  lib-y	+= io-readsw-armv3.o io-writesw-armv3.o
+else
+  lib-y	+= io-readsw-armv4.o io-writesw-armv4.o
+endif
+
+$(obj)/csumpartialcopy.o:	$(obj)/csumpartialcopygeneric.S
+$(obj)/csumpartialcopyuser.o:	$(obj)/csumpartialcopygeneric.S
+
+obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o