DFA (Dependent Failure Analysis)

JSON DFA		status: valid security: YES safety: ASIL_B
realizes: wp__sw_component_dfa
doc__json_dfa		Generic Document

Note

Use the content of the document to describe e.g. why a fault model is not applicable for the diagram.

The DFA for the component [Your Component Name] is performed. To show evidence that all failure initiators are considered, the applicability has to be filled out in the following tables. For all applicable failure initiators, the DFA has to be performed.

Dependent Failure Initiators

Shared resources

The dependent failure initiators related to shared resources are not applicable for the component. The shared resources will be considered in the platform DFA.

Communication between the two elements

Receiving function is affected by information that is false, lost, sent multiple times, or in the wrong order etc. from the sender.

Table 45 DFA communication between elements

ID	Violation cause communication between elements	Applicability	Rationale
CO_01_01	Information passed via argument through a function call, or via writing/reading a variable being global to the two software functions (data flow)	no	No shared data input for nlohman-JSON and JSON-Wrapper.
CO_01_02	Data or message corruption / repetition / loss / delay / masquerading or incorrect addressing of information	no	No messages between nlohman-JSON and JSON-Wrapper.
CO_01_03	Insertion / sequence of information	no	No messages between nlohman-JSON and JSON-Wrapper.
CO_01_04	Corruption of information, inconsistent data	no	No messages between nlohman-JSON and JSON-Wrapper.
CO_01_05	Asymmetric information sent from a sender to multiple receivers, so that not all defined receivers have the same information	no	No messages between nlohman-JSON and JSON-Wrapper.
CO_01_06	Information from a sender received by only a subset of the receivers	no	No messages between nlohman-JSON and JSON-Wrapper.
CO_01_07	Blocking access to a communication channel	no	No communication channel shared between nlohman-JSON and JSON-Wrapper.

Shared information inputs

Same information input used by multiple functions.

Table 46 DFA shared information inputs

ID	Violation cause shared information inputs	Applicability	Rationale
SI_01_02	Configuration data	no	Configuration data may be shared but should not add additional failure modes.
SI_01_03	Constants, or variables, being global to the two software functions	no	No global data is used by nlohman-JSON and JSON-Wrapper.
SI_01_04	Basic software passes data (read from hardware register and converted into logical information) to two applications software functions	no	nlohman-JSON and JSON-Wrapper are not sharing HW related data.
SI_01_05	Data / function parameter arguments / messages delivered by software function to more than one other function	no	nlohman-JSON and JSON-Wrapper are libraries incorporated by each using function individually.

Unintended impact

Unintended impacts to function due to various failures.

Table 47 DFA unintended impact

ID	Violation cause unintended impact	Applicability	Rationale
UI_01_01	Memory miss-allocation and leaks	no	Not a specific json topic, therefore covered at platform DFA.
UI_01_02	Read/Write access to memory allocated to another software element	yes	nlohman-JSON and JSON-Wrapper are in same memory space, Json component FFI (comp_saf_dfa__json__ffi)
UI_01_03	Stack/Buffer under-/overflow	no	Not a specific json topic, therefore covered at platform DFA.
UI_01_04	Deadlocks	yes	Filesystem access may be blocking, Json blocking access (comp_saf_dfa__json__blocking_access)
UI_01_05	Livelocks	no	Not a specific json topic, therefore covered at feature level.
UI_01_06	Blocking of execution	yes	nlohman-JSON and JSON-Wrapper may block each other, Json component FFI (comp_saf_dfa__json__ffi)
UI_01_07	Incorrect allocation of execution time	no	Execution time allocated by (external) OS on platform level, should be covered centrally at platform level.
UI_01_08	Incorrect execution flow	no	Execution flow controlled by (external) OS on platform level, should be covered centrally at platform level.
UI_01_09	Incorrect synchronization between software elements	no	nlohman-JSON and JSON-Wrapper have no synchronization needs.
UI_01_10	CPU time depletion	yes	nlohman-JSON and JSON-Wrapper may deplete each other’s CPU time, Json component FFI (comp_saf_dfa__json__ffi)
UI_01_11	Memory depletion	no	Not a specific json topic, therefore covered at platform DFA.
UI_01_12	Other HW unavailability	no	No special HW used for baselibs.

DFA

For all identified applicable failure initiators, the DFA is performed in the following section.

Json component FFI		status: valid
tags: baselibs, json failure_effect: nlohman-JSON and JSON-Wrapper influence each other and cause wrong read or write of Json data failure_id: UI_01_02,UI_01_06,UI_01_10 sufficient: yes mitigated_by: comp_req__json__asil violates: comp_arc_sta__baselibs__json
nlohman-JSON and JSON-Wrapper have the same ASIL.
comp_saf_dfa__json__ffi		Component DFA (Dependent Failure Analysis)

Json blocking access		status: valid
tags: baselibs, json failure_effect: nlohman-JSON and JSON-Wrapper influence each other and cause wrong read or write of Json data failure_id: UI_01_04 sufficient: yes mitigated_by: aou_req__filesystem__thread_safety violates: comp_arc_sta__baselibs__json
Json Lib is using baselibs/filesystem and has to cover the AoU about thread safety.
comp_saf_dfa__json__blocking_access		Component DFA (Dependent Failure Analysis)