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, 45 insertions, 0 deletions

diff --git a/scripts/Makefile.vdsoinst b/scripts/Makefile.vdsoinst
new file mode 100644
index 000000000..d9f724321
--- /dev/null
+++ b/scripts/Makefile.vdsoinst
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# ==========================================================================
+# Install unstripped copies of vDSO
+# ==========================================================================
+
+PHONY := __default
+__default:
+	@:
+
+include $(srctree)/scripts/Kbuild.include
+
+install-dir := $(MODLIB)/vdso
+
+define gen_install_rules
+
+dest := $(install-dir)/$$(patsubst %.dbg,%,$$(notdir $(1)))
+
+__default: $$(dest)
+$$(dest): $(1) FORCE
+	$$(call cmd,install)
+
+build-id-file := $$(shell $(READELF) -n $(1) 2>/dev/null | sed -n 's@^.*Build ID: \(..\)\(.*\)@\1/\2@p')
+
+ifneq ($$(build-id-file),)
+link := $(install-dir)/.build-id/$$(build-id-file).debug
+
+__default: $$(link)
+$$(link): $$(dest) FORCE
+	$$(call cmd,symlink)
+endif
+
+endef
+
+$(foreach x, $(sort $(INSTALL_FILES)), $(eval $(call gen_install_rules,$(x))))
+
+quiet_cmd_install = INSTALL $@
+      cmd_install = mkdir -p $(dir $@); cp $< $@
+
+quiet_cmd_symlink = SYMLINK $@
+      cmd_symlink = mkdir -p $(dir $@); ln -sf --relative $< $@
+
+PHONY += FORCE
+FORCE:
+
+.PHONY: $(PHONY)