Validate acl_to_text() input before forwarding to libacl

The acl_to_text() wrapper previously forwarded nullptr ACL handles
directly into libacl. Under ASan/UBSan builds this triggered
undefined behavior inside libacl internals before the library
returned an error condition.

Add explicit parameter validation in the wrapper and return EINVAL
for invalid ACL inputs before invoking libacl.

The related test was updated to validate the wrapper contract
directly by passing nullptr instead of relying on acl_get_file("")
to indirectly produce an invalid ACL handle.

This change improves defensive behavior for invalid input handling
and avoids sanitizer failures caused by passing invalid pointers
into third-party C library internals.

Author: nradakovic

score/os/acl_impl.cpp

@@ -400,11 +400,18 @@ score::cpp::expected<char*, score::os::Error> AclInstance::acl_to_text(const Acl
                                                               ssize_t* const len_p) const noexcept
 /* KW_SUPPRESS_END:MISRA.VAR.HIDDEN:Wrapper function is identifiable through namespace usage */
 {
+    if ((acl == nullptr) || (len_p == nullptr))
+    {
+        errno = EINVAL;
+        return score::cpp::make_unexpected(score::os::Error::createFromErrno());
+    }
+
     auto* const acl_text = ::acl_to_text(acl, len_p);
     if (acl_text == nullptr)
     {
         return score::cpp::make_unexpected(score::os::Error::createFromErrno());
     }
+
     return acl_text;
 }
 

score/os/test/acl_test.cpp

@@ -242,15 +242,14 @@ TEST_F(AclTestFixture, AclToTextToReturnErrorIfPassInvalidAcl)
     RecordProperty("Verifies", "SCR-46010294");
     RecordProperty("ASIL", "QM");
     RecordProperty("Description", "ACL shall return error if pass invalid ACL");
-    RecordProperty("TestType", "requirements-based"); // requirements test
-    RecordProperty("DerivationTechnique", "requirements-analysis"); // requirements
+    RecordProperty("TestType", "requirements-based");
+    RecordProperty("DerivationTechnique", "requirements-analysis");
 
-    auto* result = ::acl_get_file("", ACL_TYPE_ACCESS);
     ssize_t len{0};
-    auto res = unit_.acl_to_text(result, &len);
-    ASSERT_FALSE(res.has_value());
 
-    ::acl_free(result);
+    auto res = unit_.acl_to_text(nullptr, &len);
+
+    ASSERT_FALSE(res.has_value());
 }
 
 // Test to set fd return error if invalid parameters are passed