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: [e-mail]
Suggested-by: Guillaume Tucker <[e-mail]>
Signed-off-by: Kees Cook <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/lkdtm/bugs.c

···
 	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

···
 # 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

···
 #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