lkdtm/bugs: Add ARRAY_BOUNDS to selftests

Add CONFIG hints about why the ARRAY_BOUNDS test might fail, and
similarly include the CONFIGs needed to pass the ARRAY_BOUNDS test via
the selftests, and add to selftests.

Cc: kernelci@groups.io
Suggested-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210818174855.2307828-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/lkdtm/bugs.c

@@ -267,6 +267,7 @@ void lkdtm_ARRAY_BOUNDS(void)
 	kfree(not_checked);
 	kfree(checked);
 	pr_err("FAIL: survived array bounds overflow!\n");
+	pr_expected_config(CONFIG_UBSAN_BOUNDS);
 }
 
 void lkdtm_CORRUPT_LIST_ADD(void)

tools/testing/selftests/lkdtm/config

@@ -6,3 +6,5 @@ CONFIG_HARDENED_USERCOPY=y
 # CONFIG_HARDENED_USERCOPY_FALLBACK is not set
 CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
 CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y
+CONFIG_UBSAN_BOUNDS=y
+CONFIG_UBSAN_TRAP=y

tools/testing/selftests/lkdtm/tests.txt

@@ -7,6 +7,7 @@ EXCEPTION
 #EXHAUST_STACK Corrupts memory on failure
 #CORRUPT_STACK Crashes entire system on success
 #CORRUPT_STACK_STRONG Crashes entire system on success
+ARRAY_BOUNDS
 CORRUPT_LIST_ADD list_add corruption
 CORRUPT_LIST_DEL list_del corruption
 STACK_GUARD_PAGE_LEADING