From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() 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 Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- drivers/base/test/root-device-test.c | 112 +++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 drivers/base/test/root-device-test.c (limited to 'drivers/base/test/root-device-test.c') diff --git a/drivers/base/test/root-device-test.c b/drivers/base/test/root-device-test.c new file mode 100644 index 000000000..9aea23c91 --- /dev/null +++ b/drivers/base/test/root-device-test.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright 2023 Maxime Ripard + +#include + +#include + +#define DEVICE_NAME "test" + +struct test_priv { + bool probe_done; + bool release_done; + wait_queue_head_t release_wq; + struct device *dev; +}; + +static int root_device_devm_init(struct kunit *test) +{ + struct test_priv *priv; + + priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv); + init_waitqueue_head(&priv->release_wq); + + test->priv = priv; + + return 0; +} + +static void devm_device_action(void *ptr) +{ + struct test_priv *priv = ptr; + + priv->release_done = true; + wake_up_interruptible(&priv->release_wq); +} + +#define RELEASE_TIMEOUT_MS 100 + +/* + * Tests that a bus-less, non-probed device will run its device-managed + * actions when unregistered. + */ +static void root_device_devm_register_unregister_test(struct kunit *test) +{ + struct test_priv *priv = test->priv; + int ret; + + priv->dev = root_device_register(DEVICE_NAME); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->dev); + + ret = devm_add_action_or_reset(priv->dev, devm_device_action, priv); + KUNIT_ASSERT_EQ(test, ret, 0); + + root_device_unregister(priv->dev); + + ret = wait_event_interruptible_timeout(priv->release_wq, priv->release_done, + msecs_to_jiffies(RELEASE_TIMEOUT_MS)); + KUNIT_EXPECT_GT(test, ret, 0); +} + +static void devm_put_device_action(void *ptr) +{ + struct test_priv *priv = ptr; + + put_device(priv->dev); + priv->release_done = true; + wake_up_interruptible(&priv->release_wq); +} + +/* + * Tests that a bus-less, non-probed device will run its device-managed + * actions when unregistered, even if someone still holds a reference to + * it. + */ +static void root_device_devm_register_get_unregister_with_devm_test(struct kunit *test) +{ + struct test_priv *priv = test->priv; + int ret; + + priv->dev = root_device_register(DEVICE_NAME); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->dev); + + get_device(priv->dev); + + ret = devm_add_action_or_reset(priv->dev, devm_put_device_action, priv); + KUNIT_ASSERT_EQ(test, ret, 0); + + root_device_unregister(priv->dev); + + ret = wait_event_interruptible_timeout(priv->release_wq, priv->release_done, + msecs_to_jiffies(RELEASE_TIMEOUT_MS)); + KUNIT_EXPECT_GT(test, ret, 0); +} + +static struct kunit_case root_device_devm_tests[] = { + KUNIT_CASE(root_device_devm_register_unregister_test), + KUNIT_CASE(root_device_devm_register_get_unregister_with_devm_test), + {} +}; + +static struct kunit_suite root_device_devm_test_suite = { + .name = "root-device-devm", + .init = root_device_devm_init, + .test_cases = root_device_devm_tests, +}; + +kunit_test_suite(root_device_devm_test_suite); + +MODULE_DESCRIPTION("Test module for root devices"); +MODULE_AUTHOR("Maxime Ripard "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1