[silicon_creator] Initialize argument when passing it to sigverify_mod_exp_ibex()
In unit tests, the `sig` argument isn't initialized when passed on; fix
fix that.
Triggered by the following GCC 11 warning:
```
In file included from ../sw/vendor/google_googletest/googletest/include/gtest/gtest.h:376,
from ../sw/vendor/google_googletest/googlemock/include/gmock/internal/gmock-internal-utils.h:47,
from ../sw/vendor/google_googletest/googlemock/include/gmock/gmock-actions.h:144,
from ../sw/vendor/google_googletest/googlemock/include/gmock/gmock.h:59,
from ../sw/device/silicon_creator/mask_rom/rsa_verify_unittest.cc:9:
../sw/device/silicon_creator/mask_rom/rsa_verify_unittest.cc: In member function ‘virtual void rsa_verify_unittest::{anonymous}::ModExp_BadExp_Test::TestBody()’:
../sw/device/silicon_creator/mask_rom/rsa_verify_unittest.cc:365:35: error: ‘empty’ may be used uninitialized [-Werror=maybe-uninitialized]
365 | EXPECT_EQ(sigverify_mod_exp_ibex(&bad_key, &empty, &empty), false);
| ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../sw/device/silicon_creator/mask_rom/rsa_verify_unittest.cc:5:
/home/philipp/src/opentitan/sw/device/silicon_creator/mask_rom/rsa_verify.h:62:6: note: by argument 2 of type ‘const sigverify_rsa_buffer_t*’ {aka ‘const sigverify_rsa_buffer*’} to ‘bool sigverify_mod_exp_ibex(const sigverify_rsa_key_t*, const sigverify_rsa_buffer_t*, sigverify_rsa_buffer_t*)’ declared here
62 | bool sigverify_mod_exp_ibex(const sigverify_rsa_key_t *key,
| ^~~~~~~~~~~~~~~~~~~~~~
../sw/device/silicon_creator/mask_rom/rsa_verify_unittest.cc:363:26: note: ‘empty’ declared here
363 | sigverify_rsa_buffer_t empty;
| ^~~~~
```
Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/sw/device/silicon_creator/lib/sigverify_mod_exp_ibex_unittest.cc b/sw/device/silicon_creator/lib/sigverify_mod_exp_ibex_unittest.cc
index be93cf1..5d5810f 100644
--- a/sw/device/silicon_creator/lib/sigverify_mod_exp_ibex_unittest.cc
+++ b/sw/device/silicon_creator/lib/sigverify_mod_exp_ibex_unittest.cc
@@ -195,7 +195,7 @@
TEST(ModExp, BadExp) {
// Exponent = 0
constexpr sigverify_rsa_key_t bad_key{};
- sigverify_rsa_buffer_t empty;
+ sigverify_rsa_buffer_t empty{};
EXPECT_EQ(sigverify_mod_exp_ibex(&bad_key, &empty, &empty),
kErrorSigverifyBadExponent);
