[PATCH v4 RESEND 0/7] Handle faults in KUnit tests

[PATCH v4 RESEND 0/7] Handle faults in KUnit tests

[Mickaël Salaün]

Hi,

This patch series teaches KUnit to handle kthread faults as errors, and
it brings a few related fixes and improvements.

Shuah, everything should be OK now, could you please merge this series?

All these tests pass (on top of v6.8):
./tools/testing/kunit/kunit.py run --alltests
./tools/testing/kunit/kunit.py run --alltests --arch x86_64
./tools/testing/kunit/kunit.py run --alltests --arch arm64 \
  --cross_compile=aarch64-linux-gnu-

I also built and ran KUnit tests as a kernel module.

A new test case check NULL pointer dereference, which wasn't possible
before.

This is useful to test current kernel self-protection mechanisms or
future ones such as Heki: https://github.com/heki-linux

Previous versions:
v3: https://lore.kernel.org/r/20240319104857.70783-1-mic@digikod.net
v2: https://lore.kernel.org/r/20240301194037.532117-1-mic@digikod.net
v1: https://lore.kernel.org/r/20240229170409.365386-1-mic@digikod.net

Regards,

Mickaël Salaün (7):
  kunit: Handle thread creation error
  kunit: Fix kthread reference
  kunit: Fix timeout message
  kunit: Handle test faults
  kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests
  kunit: Print last test location on fault
  kunit: Add tests for fault

 include/kunit/test.h      | 24 ++++++++++++++++++---
 include/kunit/try-catch.h |  3 ---
 kernel/kthread.c          |  1 +
 lib/kunit/kunit-test.c    | 45 ++++++++++++++++++++++++++++++++++++++-
 lib/kunit/try-catch.c     | 38 ++++++++++++++++++++++-----------
 lib/kunit_iov_iter.c      | 18 ++++++++--------
 6 files changed, 101 insertions(+), 28 deletions(-)


base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
-- 
2.44.0

[PATCH v4 RESEND 1/7] kunit: Handle thread creation error

[Mickaël Salaün]

Previously, if a thread creation failed (e.g. -ENOMEM), the function was
called (kunit_catch_run_case or kunit_catch_run_case_cleanup) without
marking the test as failed.  Instead, fill try_result with the error
code returned by kthread_run(), which will mark the test as failed and
print "internal error occurred...".

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-2-mic@digikod.net
---

Changes since v2:
* Add Rae's and David's Reviewed-by.

Changes since v1:
* Add Kees's Reviewed-by.
---
 lib/kunit/try-catch.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index f7825991d576..a5cb2ef70a25 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -69,6 +69,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 				  try_catch,
 				  "kunit_try_catch_thread");
 	if (IS_ERR(task_struct)) {
+		try_catch->try_result = PTR_ERR(task_struct);
 		try_catch->catch(try_catch->context);
 		return;
 	}
-- 
2.44.0

[PATCH v4 RESEND 2/7] kunit: Fix kthread reference

[Mickaël Salaün]

There is a race condition when a kthread finishes after the deadline and
before the call to kthread_stop(), which may lead to use after free.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Fixes: adf505457032 ("kunit: fix UAF when run kfence test case test_gfpzero")
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-3-mic@digikod.net
---

Changes since v2:
* Add Fixes tag as suggested by David.
* Add David's and Rae's Reviewed-by.

Changes since v1:
* Add Kees's Reviewed-by.
---
 lib/kunit/try-catch.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index a5cb2ef70a25..73f5007f20ea 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -11,6 +11,7 @@
 #include <linux/completion.h>
 #include <linux/kernel.h>
 #include <linux/kthread.h>
+#include <linux/sched/task.h>
 
 #include "try-catch-impl.h"
 
@@ -65,14 +66,15 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 	try_catch->context = context;
 	try_catch->try_completion = &try_completion;
 	try_catch->try_result = 0;
-	task_struct = kthread_run(kunit_generic_run_threadfn_adapter,
-				  try_catch,
-				  "kunit_try_catch_thread");
+	task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
+				     try_catch, "kunit_try_catch_thread");
 	if (IS_ERR(task_struct)) {
 		try_catch->try_result = PTR_ERR(task_struct);
 		try_catch->catch(try_catch->context);
 		return;
 	}
+	get_task_struct(task_struct);
+	wake_up_process(task_struct);
 
 	time_remaining = wait_for_completion_timeout(&try_completion,
 						     kunit_test_timeout());
@@ -82,6 +84,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 		kthread_stop(task_struct);
 	}
 
+	put_task_struct(task_struct);
 	exit_code = try_catch->try_result;
 
 	if (!exit_code)
-- 
2.44.0

[PATCH v4 RESEND 3/7] kunit: Fix timeout message

[Mickaël Salaün]

The exit code is always checked, so let's properly handle the -ETIMEDOUT
error code.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-4-mic@digikod.net
---

Changes since v2:
* Add Rae's and David's Reviewed-by.

Changes since v1:
* Add Kees's Reviewed-by.
---
 lib/kunit/try-catch.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index 73f5007f20ea..cab8b24b5d5a 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -79,7 +79,6 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 	time_remaining = wait_for_completion_timeout(&try_completion,
 						     kunit_test_timeout());
 	if (time_remaining == 0) {
-		kunit_err(test, "try timed out\n");
 		try_catch->try_result = -ETIMEDOUT;
 		kthread_stop(task_struct);
 	}
@@ -94,6 +93,8 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 		try_catch->try_result = 0;
 	else if (exit_code == -EINTR)
 		kunit_err(test, "wake_up_process() was never called\n");
+	else if (exit_code == -ETIMEDOUT)
+		kunit_err(test, "try timed out\n");
 	else if (exit_code)
 		kunit_err(test, "Unknown error: %d\n", exit_code);
 
-- 
2.44.0

[PATCH v4 RESEND 4/7] kunit: Handle test faults

[Mickaël Salaün]

Previously, when a kernel test thread crashed (e.g. NULL pointer
dereference, general protection fault), the KUnit test hanged for 30
seconds and exited with a timeout error.

Fix this issue by waiting on task_struct->vfork_done instead of the
custom kunit_try_catch.try_completion, and track the execution state by
initially setting try_result with -EINTR and only setting it to 0 if
the test passed.

Fix kunit_generic_run_threadfn_adapter() signature by returning 0
instead of calling kthread_complete_and_exit().  Because thread's exit
code is never checked, always set it to 0 to make it clear.  To make
this explicit, export kthread_exit() for KUnit tests built as module.

Fix the -EINTR error message, which couldn't be reached until now.

This is tested with a following patch.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Gow <davidgow@google.com>
Tested-by: Rae Moar <rmoar@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-5-mic@digikod.net
---

Changes since v3:
* Export kthread_exit() for KUnit tests built as module, as suggested by
  David.

Changes since v2:
* s/-EFAULT/-EINTR/ in commit message as spotted by Rae.
* Add a comment explaining vfork_done as suggested by David.
* Add David's Reviewed-by.
* Add Rae's Tested-by.

Changes since v1:
* Add Kees's Reviewed-by.
---
 include/kunit/try-catch.h |  3 ---
 kernel/kthread.c          |  1 +
 lib/kunit/try-catch.c     | 19 ++++++++++++-------
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h
index c507dd43119d..7c966a1adbd3 100644
--- a/include/kunit/try-catch.h
+++ b/include/kunit/try-catch.h
@@ -14,13 +14,11 @@
 
 typedef void (*kunit_try_catch_func_t)(void *);
 
-struct completion;
 struct kunit;
 
 /**
  * struct kunit_try_catch - provides a generic way to run code which might fail.
  * @test: The test case that is currently being executed.
- * @try_completion: Completion that the control thread waits on while test runs.
  * @try_result: Contains any errno obtained while running test case.
  * @try: The function, the test case, to attempt to run.
  * @catch: The function called if @try bails out.
@@ -46,7 +44,6 @@ struct kunit;
 struct kunit_try_catch {
 	/* private: internal use only. */
 	struct kunit *test;
-	struct completion *try_completion;
 	int try_result;
 	kunit_try_catch_func_t try;
 	kunit_try_catch_func_t catch;
diff --git a/kernel/kthread.c b/kernel/kthread.c
index c5e40830c1f2..f7be976ff88a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -315,6 +315,7 @@ void __noreturn kthread_exit(long result)
 	kthread->result = result;
 	do_exit(0);
 }
+EXPORT_SYMBOL(kthread_exit);
 
 /**
  * kthread_complete_and_exit - Exit the current kthread.
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index cab8b24b5d5a..7a3910dd78a6 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -18,7 +18,7 @@
 void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
 {
 	try_catch->try_result = -EFAULT;
-	kthread_complete_and_exit(try_catch->try_completion, -EFAULT);
+	kthread_exit(0);
 }
 EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
 
@@ -26,9 +26,12 @@ static int kunit_generic_run_threadfn_adapter(void *data)
 {
 	struct kunit_try_catch *try_catch = data;
 
+	try_catch->try_result = -EINTR;
 	try_catch->try(try_catch->context);
+	if (try_catch->try_result == -EINTR)
+		try_catch->try_result = 0;
 
-	kthread_complete_and_exit(try_catch->try_completion, 0);
+	return 0;
 }
 
 static unsigned long kunit_test_timeout(void)
@@ -58,13 +61,11 @@ static unsigned long kunit_test_timeout(void)
 
 void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 {
-	DECLARE_COMPLETION_ONSTACK(try_completion);
 	struct kunit *test = try_catch->test;
 	struct task_struct *task_struct;
 	int exit_code, time_remaining;
 
 	try_catch->context = context;
-	try_catch->try_completion = &try_completion;
 	try_catch->try_result = 0;
 	task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
 				     try_catch, "kunit_try_catch_thread");
@@ -75,8 +76,12 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 	}
 	get_task_struct(task_struct);
 	wake_up_process(task_struct);
-
-	time_remaining = wait_for_completion_timeout(&try_completion,
+	/*
+	 * As for a vfork(2), task_struct->vfork_done (pointing to the
+	 * underlying kthread->exited) can be used to wait for the end of a
+	 * kernel thread.
+	 */
+	time_remaining = wait_for_completion_timeout(task_struct->vfork_done,
 						     kunit_test_timeout());
 	if (time_remaining == 0) {
 		try_catch->try_result = -ETIMEDOUT;
@@ -92,7 +97,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 	if (exit_code == -EFAULT)
 		try_catch->try_result = 0;
 	else if (exit_code == -EINTR)
-		kunit_err(test, "wake_up_process() was never called\n");
+		kunit_err(test, "try faulted\n");
 	else if (exit_code == -ETIMEDOUT)
 		kunit_err(test, "try timed out\n");
 	else if (exit_code)
-- 
2.44.0

[PATCH v4 RESEND 5/7] kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests

[Mickaël Salaün]

Fix KUNIT_SUCCESS() calls to pass a test argument.

This is a no-op for now because this macro does nothing, but it will be
required for the next commit.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-6-mic@digikod.net
---

Changes since v2:
* Add David's Reviewed-by.

Changes since v1:
* Add Kees's Reviewed-by.
---
 lib/kunit_iov_iter.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/kunit_iov_iter.c b/lib/kunit_iov_iter.c
index 859b67c4d697..27e0c8ee71d8 100644
--- a/lib/kunit_iov_iter.c
+++ b/lib/kunit_iov_iter.c
@@ -139,7 +139,7 @@ static void __init iov_kunit_copy_to_kvec(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -194,7 +194,7 @@ static void __init iov_kunit_copy_from_kvec(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 struct bvec_test_range {
@@ -302,7 +302,7 @@ static void __init iov_kunit_copy_to_bvec(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -359,7 +359,7 @@ static void __init iov_kunit_copy_from_bvec(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 static void iov_kunit_destroy_xarray(void *data)
@@ -453,7 +453,7 @@ static void __init iov_kunit_copy_to_xarray(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -516,7 +516,7 @@ static void __init iov_kunit_copy_from_xarray(struct kunit *test)
 			return;
 	}
 
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -596,7 +596,7 @@ static void __init iov_kunit_extract_pages_kvec(struct kunit *test)
 stop:
 	KUNIT_EXPECT_EQ(test, size, 0);
 	KUNIT_EXPECT_EQ(test, iter.count, 0);
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -674,7 +674,7 @@ static void __init iov_kunit_extract_pages_bvec(struct kunit *test)
 stop:
 	KUNIT_EXPECT_EQ(test, size, 0);
 	KUNIT_EXPECT_EQ(test, iter.count, 0);
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 /*
@@ -753,7 +753,7 @@ static void __init iov_kunit_extract_pages_xarray(struct kunit *test)
 	}
 
 stop:
-	KUNIT_SUCCEED();
+	KUNIT_SUCCEED(test);
 }
 
 static struct kunit_case __refdata iov_kunit_cases[] = {
-- 
2.44.0

[PATCH v4 RESEND 6/7] kunit: Print last test location on fault

[Mickaël Salaün]

This helps identify the location of test faults with opportunistic calls
to _KUNIT_SAVE_LOC().  This can be useful while writing tests or
debugging them.  It is possible to call KUNIT_SUCCESS() to explicit save
last location.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-7-mic@digikod.net
---

Changes since v3:
* Improve the try-fault error message as suggested by David.

Changes since v2:
* Extend the commit message according to discussion with David.

Changes since v1:
* Add Kees's Reviewed-by.
---
 include/kunit/test.h  | 24 +++++++++++++++++++++---
 lib/kunit/try-catch.c | 10 +++++++---
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index fcb4a4940ace..f3aa66eb0087 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -301,6 +301,8 @@ struct kunit {
 	struct list_head resources; /* Protected by lock. */
 
 	char status_comment[KUNIT_STATUS_COMMENT_SIZE];
+	/* Saves the last seen test. Useful to help with faults. */
+	struct kunit_loc last_seen;
 };
 
 static inline void kunit_set_failure(struct kunit *test)
@@ -567,6 +569,15 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
 #define kunit_err(test, fmt, ...) \
 	kunit_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
 
+/*
+ * Must be called at the beginning of each KUNIT_*_ASSERTION().
+ * Cf. KUNIT_CURRENT_LOC.
+ */
+#define _KUNIT_SAVE_LOC(test) do {					       \
+	WRITE_ONCE(test->last_seen.file, __FILE__);			       \
+	WRITE_ONCE(test->last_seen.line, __LINE__);			       \
+} while (0)
+
 /**
  * KUNIT_SUCCEED() - A no-op expectation. Only exists for code clarity.
  * @test: The test context object.
@@ -575,7 +586,7 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
  * words, it does nothing and only exists for code clarity. See
  * KUNIT_EXPECT_TRUE() for more information.
  */
-#define KUNIT_SUCCEED(test) do {} while (0)
+#define KUNIT_SUCCEED(test) _KUNIT_SAVE_LOC(test)
 
 void __noreturn __kunit_abort(struct kunit *test);
 
@@ -601,14 +612,16 @@ void __kunit_do_failed_assertion(struct kunit *test,
 } while (0)
 
 
-#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...)		       \
+#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...) do {		       \
+	_KUNIT_SAVE_LOC(test);						       \
 	_KUNIT_FAILED(test,						       \
 		      assert_type,					       \
 		      kunit_fail_assert,				       \
 		      kunit_fail_assert_format,				       \
 		      {},						       \
 		      fmt,						       \
-		      ##__VA_ARGS__)
+		      ##__VA_ARGS__);					       \
+} while (0)
 
 /**
  * KUNIT_FAIL() - Always causes a test to fail when evaluated.
@@ -637,6 +650,7 @@ void __kunit_do_failed_assertion(struct kunit *test,
 			      fmt,					       \
 			      ...)					       \
 do {									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(!!(condition_) == !!expected_true_))			       \
 		break;							       \
 									       \
@@ -698,6 +712,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(__left op __right))					       \
 		break;							       \
 									       \
@@ -758,6 +773,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely((__left) && (__right) && (strcmp(__left, __right) op 0)))   \
 		break;							       \
 									       \
@@ -791,6 +807,7 @@ do {									       \
 		.right_text = #right,					       \
 	};								       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (likely(__left && __right))					       \
 		if (likely(memcmp(__left, __right, __size) op 0))	       \
 			break;						       \
@@ -815,6 +832,7 @@ do {									       \
 do {									       \
 	const typeof(ptr) __ptr = (ptr);				       \
 									       \
+	_KUNIT_SAVE_LOC(test);						       \
 	if (!IS_ERR_OR_NULL(__ptr))					       \
 		break;							       \
 									       \
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index 7a3910dd78a6..fa687278ccc9 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -96,9 +96,13 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 
 	if (exit_code == -EFAULT)
 		try_catch->try_result = 0;
-	else if (exit_code == -EINTR)
-		kunit_err(test, "try faulted\n");
-	else if (exit_code == -ETIMEDOUT)
+	else if (exit_code == -EINTR) {
+		if (test->last_seen.file)
+			kunit_err(test, "try faulted: last line seen %s:%d\n",
+				  test->last_seen.file, test->last_seen.line);
+		else
+			kunit_err(test, "try faulted\n");
+	} else if (exit_code == -ETIMEDOUT)
 		kunit_err(test, "try timed out\n");
 	else if (exit_code)
 		kunit_err(test, "Unknown error: %d\n", exit_code);
-- 
2.44.0

[PATCH v4 RESEND 7/7] kunit: Add tests for fault

[Mickaël Salaün]

Add a test case to check NULL pointer dereference and make sure it would
result as a failed test.

The full kunit_fault test suite is marked as skipped when run on UML
because it would result to a kernel panic.

Tested with:
./tools/testing/kunit/kunit.py run --arch x86_64 kunit_fault
./tools/testing/kunit/kunit.py run --arch arm64 \
  --cross_compile=aarch64-linux-gnu- kunit_fault

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-8-mic@digikod.net
---

Changes since v2:
* Add David's Reviewed-by.

Changes since v1:
* Remove the rodata and const test cases for now.
* Replace CONFIG_X86 check with !CONFIG_UML, and remove the "_x86"
  references.
---
 lib/kunit/kunit-test.c | 45 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
index f7980ef236a3..0fdca5fffaec 100644
--- a/lib/kunit/kunit-test.c
+++ b/lib/kunit/kunit-test.c
@@ -109,6 +109,48 @@ static struct kunit_suite kunit_try_catch_test_suite = {
 	.test_cases = kunit_try_catch_test_cases,
 };
 
+#ifndef CONFIG_UML
+
+static void kunit_test_null_dereference(void *data)
+{
+	struct kunit *test = data;
+	int *null = NULL;
+
+	*null = 0;
+
+	KUNIT_FAIL(test, "This line should never be reached\n");
+}
+
+static void kunit_test_fault_null_dereference(struct kunit *test)
+{
+	struct kunit_try_catch_test_context *ctx = test->priv;
+	struct kunit_try_catch *try_catch = ctx->try_catch;
+
+	kunit_try_catch_init(try_catch,
+			     test,
+			     kunit_test_null_dereference,
+			     kunit_test_catch);
+	kunit_try_catch_run(try_catch, test);
+
+	KUNIT_EXPECT_EQ(test, try_catch->try_result, -EINTR);
+	KUNIT_EXPECT_TRUE(test, ctx->function_called);
+}
+
+#endif /* !CONFIG_UML */
+
+static struct kunit_case kunit_fault_test_cases[] = {
+#ifndef CONFIG_UML
+	KUNIT_CASE(kunit_test_fault_null_dereference),
+#endif /* !CONFIG_UML */
+	{}
+};
+
+static struct kunit_suite kunit_fault_test_suite = {
+	.name = "kunit_fault",
+	.init = kunit_try_catch_test_init,
+	.test_cases = kunit_fault_test_cases,
+};
+
 /*
  * Context for testing test managed resources
  * is_resource_initialized is used to test arbitrary resources
@@ -826,6 +868,7 @@ static struct kunit_suite kunit_current_test_suite = {
 
 kunit_test_suites(&kunit_try_catch_test_suite, &kunit_resource_test_suite,
 		  &kunit_log_test_suite, &kunit_status_test_suite,
-		  &kunit_current_test_suite, &kunit_device_test_suite);
+		  &kunit_current_test_suite, &kunit_device_test_suite,
+		  &kunit_fault_test_suite);
 
 MODULE_LICENSE("GPL v2");
-- 
2.44.0

Re: [PATCH v4 RESEND 0/7] Handle faults in KUnit tests

[Shuah Khan]

On 4/8/24 01:46, Mickaël Salaün wrote:
> Hi,
> 
> This patch series teaches KUnit to handle kthread faults as errors, and
> it brings a few related fixes and improvements.
> 
> Shuah, everything should be OK now, could you please merge this series?
> 
> All these tests pass (on top of v6.8):
> ./tools/testing/kunit/kunit.py run --alltests
> ./tools/testing/kunit/kunit.py run --alltests --arch x86_64
> ./tools/testing/kunit/kunit.py run --alltests --arch arm64 \
>    --cross_compile=aarch64-linux-gnu-
> 
> I also built and ran KUnit tests as a kernel module.
> 
> A new test case check NULL pointer dereference, which wasn't possible
> before.
> 
> This is useful to test current kernel self-protection mechanisms or
> future ones such as Heki: https://github.com/heki-linux
> 
> Previous versions:
> v3: https://lore.kernel.org/r/20240319104857.70783-1-mic@digikod.net
> v2: https://lore.kernel.org/r/20240301194037.532117-1-mic@digikod.net
> v1: https://lore.kernel.org/r/20240229170409.365386-1-mic@digikod.net
> 
> Regards,
> 
> Mickaël Salaün (7):
>    kunit: Handle thread creation error
>    kunit: Fix kthread reference
>    kunit: Fix timeout message
>    kunit: Handle test faults
>    kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests
>    kunit: Print last test location on fault
>    kunit: Add tests for fault
> 

Thank you for the resend. Applied to linux-kselftest kunit branch
for Linux 6.10-rc1.

thanks,
-- Shuah