selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 145 insertions, 0 deletions

diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig
new file mode 100644
index 000000000..94ff8e408
--- /dev/null
+++ b/lib/kunit/Kconfig
@@ -0,0 +1,145 @@
+#
+# KUnit base configuration
+#
+
+menuconfig KUNIT
+	tristate "KUnit - Enable support for unit tests"
+	select GLOB
+	help
+	  Enables support for kernel unit tests (KUnit), a lightweight unit
+	  testing and mocking framework for the Linux kernel. These tests are
+	  able to be run locally on a developer's workstation without a VM or
+	  special hardware when using UML. Can also be used on most other
+	  architectures. For more information, please see
+	  Documentation/dev-tools/kunit/.
+
+if KUNIT
+
+config KUNIT_DEBUGFS
+	bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation"
+	depends on DEBUG_FS
+	default y
+	help
+	  Enable debugfs representation for kunit.  Currently this consists
+	  of /sys/kernel/debug/kunit/<test_suite>/results files for each
+	  test suite, which allow users to see results of the last test suite
+	  run that occurred.
+
+config KUNIT_FAULT_TEST
+	bool "Enable KUnit tests which print BUG stacktraces"
+	depends on KUNIT_TEST
+	depends on !UML
+	default !PANIC_ON_OOPS
+	help
+	  Enables fault handling tests for the KUnit framework. These tests may
+	  trigger a kernel BUG(), and the associated stack trace, even when they
+	  pass. If this conflicts with your test infrastrcture (or is confusing
+	  or annoying), they can be disabled by setting this to N.
+
+config KUNIT_TEST
+	tristate "KUnit test for KUnit" if !KUNIT_ALL_TESTS
+	default KUNIT_ALL_TESTS
+	help
+	  Enables the unit tests for the KUnit test framework. These tests test
+	  the KUnit test framework itself; the tests are both written using
+	  KUnit and test KUnit. This option should only be enabled for testing
+	  purposes by developers interested in testing that KUnit works as
+	  expected.
+
+config KUNIT_EXAMPLE_TEST
+	tristate "Example test for KUnit" if !KUNIT_ALL_TESTS
+	default KUNIT_ALL_TESTS
+	help
+	  Enables an example unit test that illustrates some of the basic
+	  features of KUnit. This test only exists to help new users understand
+	  what KUnit is and how it is used. Please refer to the example test
+	  itself, lib/kunit/example-test.c, for more information. This option
+	  is intended for curious hackers who would like to understand how to
+	  use KUnit for kernel development.
+
+config KUNIT_ALL_TESTS
+	tristate "All KUnit tests with satisfied dependencies"
+	help
+	  Enables all KUnit tests, if they can be enabled.
+	  KUnit tests run during boot and output the results to the debug log
+	  in TAP format (http://testanything.org/). Only useful for kernel devs
+	  running the KUnit test harness, and not intended for inclusion into a
+	  production build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
+config KUNIT_DEFAULT_ENABLED
+	bool "Default value of kunit.enable"
+	default y
+	help
+	  Sets the default value of kunit.enable. If set to N then KUnit
+	  tests will not execute unless kunit.enable=1 is passed to the
+	  kernel command line.
+
+	  In most cases this should be left as Y. Only if additional opt-in
+	  behavior is needed should this be set to N.
+
+config KUNIT_AUTORUN_ENABLED
+	bool "Default value of kunit.autorun"
+	default y
+	help
+	  Sets the default value of kunit.autorun. If set to N then KUnit
+	  tests will not run after initialization unless kunit.autorun=1 is
+	  passed to the kernel command line. The test can still be run manually
+	  via debugfs interface.
+
+	  In most cases this should be left as Y. Only if additional opt-in
+	  behavior is needed should this be set to N.
+
+config KUNIT_DEFAULT_FILTER_GLOB
+	string "Default value of the filter_glob module parameter"
+	help
+	  Sets the default value of kunit.filter_glob. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
+config KUNIT_DEFAULT_FILTER
+	string "Default value of the filter module parameter"
+	help
+	  Sets the default value of kunit.filter. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
+config KUNIT_DEFAULT_FILTER_ACTION
+	string "Default value of the filter_action module parameter"
+	help
+	  Sets the default value of kunit.filter_action. If set to a non-empty
+	  string only matching tests are executed.
+
+	  If unsure, leave empty so all tests are executed.
+
+config KUNIT_DEFAULT_TIMEOUT
+	int "Default value of the timeout module parameter"
+	default 300
+	help
+	  Sets the default timeout, in seconds, for Kunit test cases. This value
+	  is further multiplied by a factor determined by the assigned speed
+	  setting: 1x for `DEFAULT`, 3x for `KUNIT_SPEED_SLOW`, and 12x for
+	  `KUNIT_SPEED_VERY_SLOW`. This allows slower tests on slower machines
+	  sufficient time to complete.
+
+	  If unsure, the default timeout of 300 seconds is suitable for most
+	  cases.
+
+config KUNIT_UML_PCI
+	bool "KUnit UML PCI Support"
+	depends on UML
+	select UML_PCI
+	help
+	  Enables the PCI subsystem on UML for use by KUnit tests.
+	  Some KUnit tests require the PCI core which is not enabled by
+	  default on UML.
+
+	  If unsure, say N.
+
+endif # KUNIT