[PATCH] lkdtm/bugs: Don't expect thread termination without CONFIG_UBSAN_TRAP

[Christophe Leroy]

When you don't select CONFIG_UBSAN_TRAP, you get:

  # echo ARRAY_BOUNDS > /sys/kernel/debug/provoke-crash/DIRECT
[  102.265827] ================================================================================
[  102.278433] UBSAN: array-index-out-of-bounds in drivers/misc/lkdtm/bugs.c:342:16
[  102.287207] index 8 is out of range for type 'char [8]'
[  102.298722] ================================================================================
[  102.313712] lkdtm: FAIL: survived array bounds overflow!
[  102.318770] lkdtm: Unexpected! This kernel (5.16.0-rc1-s3k-dev-01884-g720dcf79314a ppc) was built with CONFIG_UBSAN_BOUNDS=y

It is not correct because when CONFIG_UBSAN_TRAP is not selected
you can't expect array bounds overflow to kill the thread.

Modify the logic so that when the kernel is built with
CONFIG_UBSAN_BOUNDS but without CONFIG_UBSAN_TRAP, you get a warning
about CONFIG_UBSAN_TRAP not been selected instead.

Fixes: c75be56e35b2 ("lkdtm/bugs: Add ARRAY_BOUNDS to selftests")
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 drivers/misc/lkdtm/bugs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index f21854ac5cc2..0f4dd9621b75 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -346,7 +346,10 @@ void lkdtm_ARRAY_BOUNDS(void)
 	kfree(not_checked);
 	kfree(checked);
 	pr_err("FAIL: survived array bounds overflow!\n");
-	pr_expected_config(CONFIG_UBSAN_BOUNDS);
+	if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
+		pr_expected_config(CONFIG_UBSAN_TRAP);
+	else
+		pr_expected_config(CONFIG_UBSAN_BOUNDS);
 }
 
 void lkdtm_CORRUPT_LIST_ADD(void)
-- 
2.35.1