Control-flow checking by software signatures

摘要

This paper presents a new signature monitoring technique, CFCSSn(control flow checking by software signatures); CFCSS is a pure softwarenmethod that checks the control flow of a program using assignednsignatures. An algorithm assigns a unique signature to each node in thenprogram graph and adds instructions for error detection. Signatures arenembedded in the program during compilation time using the constant fieldnof the instructions and compared with run-time signatures when thenprogram is executed. Another algorithm reduces the code size andnexecution time overhead caused by checking instructions in CFCSS. An"branching fault injection experiment" was performed with benchmarknprograms. Without CFCSS, an average of 33.7 % of the injected branchingnfaults produced undetected incorrect outputs; however, with CFCSS, onlyn3.1 % of branching faults produced undetected incorrect outputs. Thus itnis possible to increase error detection coverage for control flow errorsnby an order of magnitude using CFCSS. The distinctive advantage of CFCSSnover previous signature monitoring techniques is that CFCSS is a purensoftware method, i.e., it needs no dedicated hardware such as a watchdognprocessor for control flow checking. A watchdog task in multitaskingnenvironment also needs no extra hardware, but the advantage of CFCSSnover a watchdog task is that CFCSS can be used even when the operatingnsystem does not support multitasking