torture: talloc_string_sub tests for utf-8 brevity

If we allow overly long UTF-8 sequences (in the tests, encoding '\0'
as 2, 3, or 4 bytes), it might be possible for bad strings to slip
through.

We fail. But wait for the next commit.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14684

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>

lib/util/tests/str.c

@@ -91,6 +91,52 @@ static bool test_talloc_string_sub_multiple(struct torture_context *tctx)
 	return true;
 }
 
+/*
+ * with these next three tests, the failure is that the pattern looks like
+ * "+++" because the \x.. bytes encode a zero byte in UTF-8. If we are not
+ * careful with these strings we will see crashes instead of failures.
+ */
+
+static bool test_talloc_string_sub_tricky_utf8_4(struct torture_context *tctx)
+{
+	const char string[] =  "++++--\xD8\xBB";
+	const char pattern[] = "+++\xF0\x80\x80\x80++";
+	const char replace[] = "...";
+
+	char *t = talloc_string_sub(tctx, string, pattern, replace);
+	torture_assert_str_equal(tctx, t, string,
+				 "should reject 4 byte NUL char");
+	talloc_free(t);
+	return true;
+}
+
+static bool test_talloc_string_sub_tricky_utf8_3(struct torture_context *tctx)
+{
+	const char string[] =  "++++--\xD8\xBB";
+	const char pattern[] = "+++\xE0\x80\x80++";
+	const char replace[] = "...";
+
+	char *t = talloc_string_sub(tctx, string, pattern, replace);
+	torture_assert_str_equal(tctx, t, string,
+				 "should reject 3 byte NUL char");
+	talloc_free(t);
+	return true;
+}
+
+static bool test_talloc_string_sub_tricky_utf8_2(struct torture_context *tctx)
+{
+	const char string[] =  "++++--\xD8\xBB";
+	const char pattern[] = "+++\xC0\x80++";
+	const char replace[] = "...";
+
+	char *t = talloc_string_sub(tctx, string, pattern, replace);
+	torture_assert_str_equal(tctx, t, string,
+				 "should reject 2 byte NUL char");
+	talloc_free(t);
+	return true;
+}
+
+
 
 
 struct torture_suite *torture_local_util_str(TALLOC_CTX *mem_ctx)
@@ -118,5 +164,17 @@ struct torture_suite *torture_local_util_str(TALLOC_CTX *mem_ctx)
 	torture_suite_add_simple_test(suite, "string_sub_talloc_multiple", 
 				      test_talloc_string_sub_multiple);
 
+	torture_suite_add_simple_test(suite,
+				      "test_talloc_string_sub_tricky_utf8_4",
+				      test_talloc_string_sub_tricky_utf8_4);
+
+	torture_suite_add_simple_test(suite,
+				      "test_talloc_string_sub_tricky_utf8_3",
+				      test_talloc_string_sub_tricky_utf8_3);
+
+	torture_suite_add_simple_test(suite,
+				      "test_talloc_string_sub_tricky_utf8_2",
+				      test_talloc_string_sub_tricky_utf8_2);
+
 	return suite;
 }

selftest/knownfail.d/str-utf8

@@ -0,0 +1 @@
+^samba4.local.str.+utf8_[234]