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>

7 files changed, 54 insertions, 0 deletions

diff --git a/scripts/kconfig/tests/choice/Kconfig b/scripts/kconfig/tests/choice/Kconfig
new file mode 100644
index 000000000..cd252579a
--- /dev/null
+++ b/scripts/kconfig/tests/choice/Kconfig
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+
+choice
+	prompt "boolean choice"
+	default BOOL_CHOICE1
+
+config BOOL_CHOICE0
+	bool "choice 0"
+
+config BOOL_CHOICE1
+	bool "choice 1"
+
+endchoice
diff --git a/scripts/kconfig/tests/choice/__init__.py b/scripts/kconfig/tests/choice/__init__.py
new file mode 100644
index 000000000..0fc7bf9b5
--- /dev/null
+++ b/scripts/kconfig/tests/choice/__init__.py
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0
+"""
+Basic choice tests.
+"""
+
+
+def test_oldask0(conf):
+    assert conf.oldaskconfig() == 0
+    assert conf.stdout_contains('oldask0_expected_stdout')
+
+
+def test_allyes(conf):
+    assert conf.allyesconfig() == 0
+    assert conf.config_contains('allyes_expected_config')
+
+
+def test_allmod(conf):
+    assert conf.allmodconfig() == 0
+    assert conf.config_contains('allmod_expected_config')
+
+
+def test_allno(conf):
+    assert conf.allnoconfig() == 0
+    assert conf.config_contains('allno_expected_config')
+
+
+def test_alldef(conf):
+    assert conf.alldefconfig() == 0
+    assert conf.config_contains('alldef_expected_config')
diff --git a/scripts/kconfig/tests/choice/alldef_expected_config b/scripts/kconfig/tests/choice/alldef_expected_config
new file mode 100644
index 000000000..b359a2e64
--- /dev/null
+++ b/scripts/kconfig/tests/choice/alldef_expected_config
@@ -0,0 +1,2 @@
+# CONFIG_BOOL_CHOICE0 is not set
+CONFIG_BOOL_CHOICE1=y
diff --git a/scripts/kconfig/tests/choice/allmod_expected_config b/scripts/kconfig/tests/choice/allmod_expected_config
new file mode 100644
index 000000000..b359a2e64
--- /dev/null
+++ b/scripts/kconfig/tests/choice/allmod_expected_config
@@ -0,0 +1,2 @@
+# CONFIG_BOOL_CHOICE0 is not set
+CONFIG_BOOL_CHOICE1=y
diff --git a/scripts/kconfig/tests/choice/allno_expected_config b/scripts/kconfig/tests/choice/allno_expected_config
new file mode 100644
index 000000000..b359a2e64
--- /dev/null
+++ b/scripts/kconfig/tests/choice/allno_expected_config
@@ -0,0 +1,2 @@
+# CONFIG_BOOL_CHOICE0 is not set
+CONFIG_BOOL_CHOICE1=y
diff --git a/scripts/kconfig/tests/choice/allyes_expected_config b/scripts/kconfig/tests/choice/allyes_expected_config
new file mode 100644
index 000000000..b359a2e64
--- /dev/null
+++ b/scripts/kconfig/tests/choice/allyes_expected_config
@@ -0,0 +1,2 @@
+# CONFIG_BOOL_CHOICE0 is not set
+CONFIG_BOOL_CHOICE1=y
diff --git a/scripts/kconfig/tests/choice/oldask0_expected_stdout b/scripts/kconfig/tests/choice/oldask0_expected_stdout
new file mode 100644
index 000000000..80ec34c61
--- /dev/null
+++ b/scripts/kconfig/tests/choice/oldask0_expected_stdout
@@ -0,0 +1,4 @@
+boolean choice
+  1. choice 0 (BOOL_CHOICE0) (NEW)
+> 2. choice 1 (BOOL_CHOICE1) (NEW)
+choice[1-2?]: