Eliminating redundant bounds checks in dynamic buffer overflow detection using weakest preconditions

Publisher:
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Publication Type:
Journal Article
Citation:
IEEE Transactions on Reliability, 2016, 65, (4), pp. 1682-1699
Issue Date:
2016-12-01
Full metadata record
Spatial errors (e.g., buffer overflows) continue to be one of the dominant threats to software reliability and security in C/C++ programs. Presently, the software industry typically enforces spatial memory safety by instrumentation. Due to high overheads incurred in bounds checking at runtime, many program inputs cannot be exercised, causing some input-specific spatial errors to go undetected in today's commercial software. This paper introduces a new compile-time approach for reducing bounds checking overheads based on the notion of weakest precondition (WP). The basic idea is to guard a bounds check at a pointer dereference inside a loop, where the WP-based guard is hoisted outside the loop, so that its falsehood implies the absence of out-of-bounds errors at the dereference, thereby avoiding the corresponding bounds check inside the loop. This WP-based approach is applicable to any spatial-error detection approach (in software or hardware or both). To evaluate the effectiveness of our approach, we take SoftBound, a compile-time tool with an open-source implementation in low-level virtual machine (LLVM), as our baseline. SoftBound adopts a pointer-based checking scheme with disjoint metadata, making it a state-of-the-art tool in providing compatible and complete spatial safety for C. Our new tool, called WPBound, is a refined version of SoftBound, also implemented in LLVM, by incorporating our WP-based compiler approach comprising both intra and interprocedural optimizations. For a set of 20 C benchmarks selected from SPEC and MiBench,WPBound reduces the average runtime overhead of SoftB ound from 77% to 47% (by a reduction of 39%), with small code size increases.
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