Re: [RFC PATCH 2/2] KUnit: KASAN Integration

On Thu, Feb 27, 2020 at 3:44 AM 'Patricia Alfonso' via kasan-dev kasan-dev@googlegroups.com wrote:

Integrate KASAN into KUnit testing framework.

• Fail tests when KASAN reports an error that is not expected
• Use KUNIT_EXPECT_KASAN_FAIL to expect a KASAN error in KASAN tests
• KUnit struct added to current task to keep track of the current test

from KASAN code

• Booleans representing if a KASAN report is expected and if a KASAN

report is found added to kunit struct

• This prints "line# has passed" or "line# has failed"

Signed-off-by: Patricia Alfonso trishalfonso@google.com

If anyone has any suggestions on how best to print the failure messages, please share!

One issue I have found while testing this is the allocation fails in kmalloc_pagealloc_oob_right() sometimes, but not consistently. This does cause the test to fail on the KUnit side, as expected, but it seems to skip all the tests before this one because the output starts with this failure instead of with the first test, kmalloc_oob_right().

include/kunit/test.h | 24 ++++++++++++++++++++++++ include/linux/sched.h | 7 ++++++- lib/kunit/test.c | 7 ++++++- mm/kasan/report.c | 19 +++++++++++++++++++ tools/testing/kunit/kunit_kernel.py | 2 +- 5 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h index 2dfb550c6723..2e388f8937f3 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -21,6 +21,8 @@ struct kunit_resource; typedef int (*kunit_resource_init_t)(struct kunit_resource *, void *); typedef void (*kunit_resource_free_t)(struct kunit_resource *);

+void kunit_set_failure(struct kunit *test);

/**

• struct kunit_resource - represents a *test managed resource*
• @allocation: for the user to store arbitrary data.

@@ -191,6 +193,9 @@ struct kunit { * protect it with some type of lock. */ struct list_head resources; /* Protected by lock. */

•   bool kasan_report_expected;
  

•   bool kasan_report_found;
  

};

void kunit_init_test(struct kunit *test, const char *name); @@ -941,6 +946,25 @@ do { \ ptr, \ NULL)

+/**

• • KUNIT_EXPECT_KASAN_FAIL() - Causes a test failure when the expression does
• • not cause a KASAN error.
• */

+#define KUNIT_EXPECT_KASAN_FAIL(test, condition) do { \

•   test->kasan_report_expected = true;     \
  

•   test->kasan_report_found = false; \
  

•   condition; \
  

•   if (test->kasan_report_found == test->kasan_report_expected) { \
  

•           pr_info("%d has passed", __LINE__); \
  

•   } else { \
  

•           kunit_set_failure(test); \
  

•           pr_info("%d has failed", __LINE__); \
  

•   } \
  

•   test->kasan_report_expected = false;    \
  

•   test->kasan_report_found = false;       \
  

+} while (0)

/**

• KUNIT_EXPECT_TRUE() - Causes a test failure when the expression is not true.
• @test: The test context object.

diff --git a/include/linux/sched.h b/include/linux/sched.h index 04278493bf15..db23d56061e7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -32,6 +32,8 @@ #include <linux/posix-timers.h> #include <linux/rseq.h>

+#include <kunit/test.h>

/* task_struct member predeclarations (sorted alphabetically): */ struct audit_context; struct backing_dev_info; @@ -1178,7 +1180,10 @@ struct task_struct {

#ifdef CONFIG_KASAN unsigned int kasan_depth; -#endif +#ifdef CONFIG_KUNIT

•   struct kunit *kasan_kunit_test;
  

+#endif /* CONFIG_KUNIT */ +#endif /* CONFIG_KASAN */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* Index of current stored address in ret_stack: */ diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 9242f932896c..d266b9495c67 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -9,11 +9,12 @@ #include <kunit/test.h> #include <linux/kernel.h> #include <linux/sched/debug.h> +#include <linux/sched.h>

#include "string-stream.h" #include "try-catch-impl.h"

-static void kunit_set_failure(struct kunit *test) +void kunit_set_failure(struct kunit *test) { WRITE_ONCE(test->success, false); } @@ -236,6 +237,10 @@ static void kunit_try_run_case(void *data) struct kunit_suite *suite = ctx->suite; struct kunit_case *test_case = ctx->test_case;

+#ifdef CONFIG_KASAN

•   current->kasan_kunit_test = test;
  

+#endif

•   /*
     * kunit_run_case_internal may encounter a fatal error; if it does,
     * abort will be called, this thread will exit, and finally the parent
  

diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 5ef9f24f566b..5554d23799a5 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -32,6 +32,8 @@

#include <asm/sections.h>

+#include <kunit/test.h>

#include "kasan.h" #include "../slab.h"

@@ -461,6 +463,15 @@ void kasan_report_invalid_free(void *object, unsigned long ip) u8 tag = get_tag(object);

    object = reset_tag(object);

•   if (current->kasan_kunit_test) {
  

•           if (current->kasan_kunit_test->kasan_report_expected) {
  

•                   current->kasan_kunit_test->kasan_report_found = true;
  

•                   return;
  

I think we need to continue and print KASAN report even in this case. 2 reasons: - tests don't check validity of printed reports, but at least human can verify sanity of the report - report printing code also needs to be tested, at least that it does not crash/hang If we don't print reports, it may look nicer, but will be less useful.

•           }
  

•           kunit_set_failure(current->kasan_kunit_test);
  

•   }