kasan: fail non-kasan KUnit tests on KASAN reports

After the recent changes done to KUnit-enabled KASAN tests, non-KASAN
KUnit tests stopped being failed when KASAN report is detected.

Recover that property by failing the currently running non-KASAN KUnit
test when KASAN detects and prints a report for a bad memory access.

Note that if the bad accesses happened in a kernel thread that doesn't
have a reference to the currently running KUnit-test available via
current->kunit_test, the test won't be failed.  This is a limitation of
KUnit, which doesn't yet provide a thread-agnostic way to find the
reference to the currenly running test.

Link: https://lkml.kernel.org/r/7be29a8ea967cee6b7e48d3d5a242d1d0bd96851.1669820505.git.andreyknvl@google.com
Fixes: 49d9977a ("kasan: check CONFIG_KASAN_KUNIT_TEST instead of CONFIG_KUNIT")
Fixes: 7ce0ea19 ("kasan: switch kunit tests to console tracepoints")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: David Gow <davidgow@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/kasan.h

@@ -541,6 +541,18 @@ static inline bool kasan_arch_is_ready(void)	{ return true; }
 #error kasan_arch_is_ready only works in KASAN generic outline mode!
 #endif
 
+#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+void kasan_kunit_test_suite_start(void);
+void kasan_kunit_test_suite_end(void);
+
+#else /* CONFIG_KASAN_KUNIT_TEST */
+
+static inline void kasan_kunit_test_suite_start(void) { }
+static inline void kasan_kunit_test_suite_end(void) { }
+
+#endif /* CONFIG_KASAN_KUNIT_TEST */
+
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) || IS_ENABLED(CONFIG_KASAN_MODULE_TEST)
 
 bool kasan_save_enable_multi_shot(void);

mm/kasan/kasan_test.c

@@ -76,6 +76,9 @@ static int kasan_suite_init(struct kunit_suite *suite)
 		return -1;
 	}
 
+	/* Stop failing KUnit tests on KASAN reports. */
+	kasan_kunit_test_suite_start();
+
 	/*
 	 * Temporarily enable multi-shot mode. Otherwise, KASAN would only
 	 * report the first detected bug and panic the kernel if panic_on_warn
@@ -94,6 +97,7 @@ static int kasan_suite_init(struct kunit_suite *suite)
 
 static void kasan_suite_exit(struct kunit_suite *suite)
 {
+	kasan_kunit_test_suite_end();
 	kasan_restore_multi_shot(multishot);
 	for_each_kernel_tracepoint(unregister_tracepoints, NULL);
 	tracepoint_synchronize_unregister();

mm/kasan/report.c

@@ -9,6 +9,7 @@
  *        Andrey Konovalov <andreyknvl@gmail.com>
  */
 
+#include <kunit/test.h>
 #include <linux/bitops.h>
 #include <linux/ftrace.h>
 #include <linux/init.h>
@@ -112,10 +113,62 @@ EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
 
 #endif
 
+#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+
+/*
+ * Whether the KASAN KUnit test suite is currently being executed.
+ * Updated in kasan_test.c.
+ */
+bool kasan_kunit_executing;
+
+void kasan_kunit_test_suite_start(void)
+{
+	WRITE_ONCE(kasan_kunit_executing, true);
+}
+EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_start);
+
+void kasan_kunit_test_suite_end(void)
+{
+	WRITE_ONCE(kasan_kunit_executing, false);
+}
+EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_end);
+
+static bool kasan_kunit_test_suite_executing(void)
+{
+	return READ_ONCE(kasan_kunit_executing);
+}
+
+#else /* CONFIG_KASAN_KUNIT_TEST */
+
+static inline bool kasan_kunit_test_suite_executing(void) { return false; }
+
+#endif /* CONFIG_KASAN_KUNIT_TEST */
+
+#if IS_ENABLED(CONFIG_KUNIT)
+
+static void fail_non_kasan_kunit_test(void)
+{
+	struct kunit *test;
+
+	if (kasan_kunit_test_suite_executing())
+		return;
+
+	test = current->kunit_test;
+	if (test)
+		kunit_set_failure(test);
+}
+
+#else /* CONFIG_KUNIT */
+
+static inline void fail_non_kasan_kunit_test(void) { }
+
+#endif /* CONFIG_KUNIT */
+
 static DEFINE_SPINLOCK(report_lock);
 
 static void start_report(unsigned long *flags, bool sync)
 {
+	fail_non_kasan_kunit_test();
 	/* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
 	disable_trace_on_warning();
 	/* Do not allow LOCKDEP mangling KASAN reports. */