{"record":{"id":"a9ff6b74ba7a94bd","repo":"puppetlabs/puppet","slug":"convertsidtostringsidw-failed-to-allocate-buffer-f","errorCode":null,"errorMessage":"ConvertSidToStringSidW failed to allocate buffer for sid","messagePattern":"ConvertSidToStringSidW failed to allocate buffer for sid","errorType":"exception","errorClass":"Puppet::Error","httpStatus":null,"severity":"error","filePath":"lib/puppet/util/windows/sid.rb","lineNumber":174,"sourceCode":"\n    # https://stackoverflow.com/a/1792930 - 68 bytes, 184 characters in a string\n    MAXIMUM_SID_STRING_LENGTH = 184\n\n    # Convert a SID pointer to a SID string, e.g. \"S-1-5-32-544\".\n    def sid_ptr_to_string(psid)\n      if !psid.is_a?(FFI::Pointer) || IsValidSid(psid) == FFI::WIN32_FALSE\n        raise Puppet::Util::Windows::Error, _(\"Invalid SID\")\n      end\n\n      sid_string = nil\n      FFI::MemoryPointer.new(:pointer, 1) do |buffer_ptr|\n        if ConvertSidToStringSidW(psid, buffer_ptr) == FFI::WIN32_FALSE\n          raise Puppet::Util::Windows::Error, _(\"Failed to convert binary SID\")\n        end\n\n        buffer_ptr.read_win32_local_pointer do |wide_string_ptr|\n          if wide_string_ptr.null?\n            raise Puppet::Error, _(\"ConvertSidToStringSidW failed to allocate buffer for sid\")\n          end\n\n          sid_string = wide_string_ptr.read_arbitrary_wide_string_up_to(MAXIMUM_SID_STRING_LENGTH)\n        end\n      end\n\n      sid_string\n    end\n    module_function :sid_ptr_to_string\n\n    # Convert a SID string, e.g. \"S-1-5-32-544\" to a pointer (containing the\n    # address of the binary SID structure). The returned value can be used in\n    # Win32 APIs that expect a PSID, e.g. IsValidSid. The account for this\n    # SID may or may not exist.\n    def string_to_sid_ptr(string_sid, &block)\n      FFI::MemoryPointer.from_string_to_wide_string(string_sid) do |lpcwstr|\n        FFI::MemoryPointer.new(:pointer, 1) do |sid_ptr_ptr|\n          if ConvertStringSidToSidW(lpcwstr, sid_ptr_ptr) == FFI::WIN32_FALSE","sourceCodeStart":156,"sourceCodeEnd":192,"githubUrl":"https://github.com/puppetlabs/puppet/blob/e227c27540975c25aa22d533a52424a9d2fc886a/lib/puppet/util/windows/sid.rb#L156-L192","documentation":"Raised by Puppet::Util::Windows::SID.sid_ptr_to_string when ConvertSidToStringSidW reported success but the returned string buffer pointer read via read_win32_local_pointer is NULL. It is a plain Puppet::Error (no Win32 code available) flagging that no buffer was allocated for the SID string.","triggerScenarios":"Inconsistent API behavior where the conversion returns TRUE yet the out-pointer is null — practically limited to broken native environments, shimmed/mocked FFI in tests, or memory corruption overwriting the out-parameter.","commonSituations":"Unit tests with stubbed FFI functions returning success without setting the pointer; native memory corruption from a separate loaded extension; exotic terminal-services/RDP contexts where local allocation semantics misbehave. Nearly never seen on healthy systems.","solutions":["If seen in tests, fix the FFI stub to populate the out-pointer (write a valid local pointer).","Restart the process — one-off null returns point to transient native state.","Investigate memory corruption if other native calls misbehave in the same process.","Render the SID manually from its sub-authorities as a workaround."],"exampleFix":"// exampleFix not applicable - defensive internal check\nnull","handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"begin\n  s = Puppet::Util::Windows::SID.sid_ptr_to_string(ptr)\nrescue Puppet::Error => e\n  raise unless e.message.include?('failed to allocate buffer for sid')\n  raise 'native allocator returned null; restart process or check for memory corruption'\nend","preventionTips":["Keep FFI test doubles realistic (populate out-pointers on success).","Restart long-lived agents exhibiting native anomalies rather than looping on the error."],"tags":["windows","sid","ffi","allocation","puppet"],"backgroundTag":"memory-allocation-failed","analyzedSha":"e227c27540975c25aa22d533a52424a9d2fc886a","analyzedAt":"2026-08-21T20:49:46.650Z","schemaVersion":2},"datasetVersion":"2026-08-21T23:17:16.201Z"}