tests: fix compilation failures

Attempts to access array of fixed size beyond the boundary now trigger
compilation warnings, even though there is room beyond the array
boundary in due to data layout.

Let's modify the code to declare the array size explicitly to calm the
compiler.

Also needed to add en explicit return value in a function where all
returns happened inside a case statement.

BRANCH=none
BUG=none
TEST='make run2tests' does not fail to compile any more and succeeds
     running tests.

Change-Id: Ib2158145233a0e8641c5b9b95499928f18390a8d
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3120000
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

3 files changed, 34 insertions, 20 deletions

diff --git a/tests/vb2_common2_tests.c b/tests/vb2_common2_tests.c
index 3f062892..5f065f8f 100644
--- a/tests/vb2_common2_tests.c
+++ b/tests/vb2_common2_tests.c
@@ -41,6 +41,7 @@ static vb2_error_t hwcrypto_mock(enum hwcrypto_state *state)
 			/* shouldn't reach here but added for compiler */
 			return VB2_ERROR_MOCK;
 	}
+	return VB2_ERROR_MOCK;
 }
 
 vb2_error_t vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
diff --git a/tests/vb2_sha256_x86_tests.c b/tests/vb2_sha256_x86_tests.c
index 98be77ef..ca934e47 100644
--- a/tests/vb2_sha256_x86_tests.c
+++ b/tests/vb2_sha256_x86_tests.c
@@ -71,22 +71,29 @@ static void sha256_tests(void)
 static void known_value_tests(void)
 {
 	const char sentinel[] = "keepme";
-	struct {
+	union {
 		struct vb2_hash hash;
-		uint8_t overflow[8];
+		char overflow[sizeof(struct vb2_hash) + 8];
 	} test;
 
 #define TEST_KNOWN_VALUE(algo, str, value) \
 	TEST_EQ(vb2_digest_size(algo), sizeof(value) - 1, \
-		"Known hash size " #algo ": " #str); \
-	strcpy((char *)&test.hash.raw[sizeof(value) - 1], sentinel); \
-	TEST_SUCC(vb2_digest_buffer((const uint8_t *)str, sizeof(str) - 1, \
-					algo, test.hash.raw, vb2_digest_size(algo)), \
-		  "Calculate known hash " #algo ": " #str); \
-	TEST_EQ(memcmp(test.hash.raw, value, sizeof(value) - 1), 0, \
-		"Known hash " #algo ": " #str); \
-	TEST_EQ(strcmp((char *)&test.hash.raw[sizeof(value) - 1], sentinel), 0,\
-		"Overflow known hash " #algo ": " #str);
+		"Known hash size " #algo ": " #str);			\
+	{								\
+		char *sent_base = test.overflow +			\
+			offsetof(struct vb2_hash, raw) + sizeof(value) - 1; \
+		strcpy(sent_base, sentinel);				\
+		strcpy(sent_base, sentinel);				\
+		TEST_SUCC(vb2_digest_buffer((const uint8_t *)str,	\
+					    sizeof(str) - 1,		\
+					    algo, test.hash.raw,	\
+					    vb2_digest_size(algo)),	\
+			  "Calculate known hash " #algo ": " #str);	\
+		TEST_EQ(memcmp(test.hash.raw, value, sizeof(value) - 1), 0, \
+			"Known hash " #algo ": " #str);			\
+		TEST_EQ(strcmp(sent_base, sentinel), 0,			\
+			"Overflow known hash " #algo ": " #str);	\
+	}
 
 	TEST_KNOWN_VALUE(VB2_HASH_SHA256, "",
 		"\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9"
diff --git a/tests/vb2_sha_tests.c b/tests/vb2_sha_tests.c
index b4a4bd06..a14af65c 100644
--- a/tests/vb2_sha_tests.c
+++ b/tests/vb2_sha_tests.c
@@ -172,21 +172,27 @@ static void misc_tests(void)
 static void known_value_tests(void)
 {
 	const char sentinel[] = "keepme";
-	struct {
+	union {
 		struct vb2_hash hash;
-		uint8_t overflow[8];
+		char overflow[sizeof(struct vb2_hash) + 8];
 	} test;
 
+
 #define TEST_KNOWN_VALUE(algo, str, value) \
 	TEST_EQ(vb2_digest_size(algo), sizeof(value) - 1, \
 		"Known hash size " #algo ": " #str); \
-	strcpy((char *)&test.hash.raw[sizeof(value) - 1], sentinel); \
-	TEST_SUCC(vb2_hash_calculate(str, sizeof(str) - 1, algo, &test.hash), \
-		  "Calculate known hash " #algo ": " #str); \
-	TEST_EQ(memcmp(test.hash.raw, value, sizeof(value) - 1), 0, \
-		"Known hash " #algo ": " #str); \
-	TEST_EQ(strcmp((char *)&test.hash.raw[sizeof(value) - 1], sentinel), 0,\
-		"Overflow known hash " #algo ": " #str);
+	{								\
+		char *sent_base = test.overflow + \
+			offsetof(struct vb2_hash, raw) + sizeof(value) - 1; \
+		strcpy(sent_base, sentinel);				\
+		TEST_SUCC(vb2_hash_calculate(str, sizeof(str) - 1,	\
+					     algo, &test.hash),		\
+			  "Calculate known hash " #algo ": " #str);	\
+		TEST_EQ(memcmp(test.hash.raw, value, sizeof(value) - 1), 0, \
+			"Known hash " #algo ": " #str);			\
+		TEST_EQ(strcmp(sent_base, sentinel), 0,			\
+			"Overflow known hash " #algo ": " #str);	\
+	}
 
 	TEST_KNOWN_VALUE(VB2_HASH_SHA1, "",
 		"\xda\x39\xa3\xee\x5e\x6b\x4b\x0d\x32\x55\xbf\xef\x95\x60\x18"