ubsan: Silence W=1 warnings in self-test

Silence a handful of W=1 warnings in the UBSan selftest, which set variables without using them. For example:

lib/test_ubsan.c:101:6: warning: variable 'val1' set but not used [-Wunused-but-set-variable]

     101 |         int val1 = 10;
         |             ^

Reported-by kernel test robot <[email protected]>

Closes https://lore.kernel.org/oe-kbuild-all/[email protected]/ open here

Signed-off-by Kees Cook <[email protected]>

---
v2:
- add additional "volatile" annotations for potential future proofing (marco)
v1: https://lore.kernel.org/all/[email protected]/

---
 lib/Makefile     | 1 +
 lib/test_ubsan.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

lib/Makefile +1 -0

index 6b09731d8e61..bc36a5c167db 100644
@@ -69,6 +69,7 @@ obj-$(CONFIG_HASH_KUNIT_TEST) += test_hash.o
 obj-$(CONFIG_TEST_IDA) += test_ida.o
 obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
 CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla)
+CFLAGS_test_ubsan.o += $(call cc-disable-warning, unused-but-set-variable)
 UBSAN_SANITIZE_test_ubsan.o := y
 obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
 obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o

lib/test_ubsan.c +2 -3

index 2062be1f2e80..f4ee2484d4b5 100644
@@ -23,8 +23,8 @@ static void test_ubsan_divrem_overflow(void)
 static void test_ubsan_shift_out_of_bounds(void)
 {
        volatile int neg = -1, wrap = 4;
-       int val1 = 10;
-       int val2 = INT_MAX;
+       volatile int val1 = 10;
+       volatile int val2 = INT_MAX;
 
        UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
        val1 <<= neg;
--

2.34.1

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