Fawkes: Finding Data Durability Bugs in DBMSs via Recovered Data State Verification

Data durability is a fundamental requirement in DBMSs, ensuring that committed data remains intact despite unexpected faults such as power failures. Despite its critical importance, implementations of durability and recovery mechanisms continue to exhibit flaws, leading to severe issues(e.g., data loss, data inconsistency), which we refer to as Data Durability Bugs (DDBs). However, there is a limited understanding of the characteristics and root causes of DDBs. Furthermore, existing testing methods(e.g., Mallory) are often inadequate for detecting DDBs, particularly those that cause data loss or data inconsistency following DBMS failures.

This paper presents a comprehensive study of 43 DDBs across four widely used DBMSs. It reveals that DDBs primarily manifest as data loss, data inconsistency, log corruption, and system unavailability, often stem from flawed durability and recovery mechanisms, and are typically triggered when faults occur during filesystem or kernel-level calls. Based on these findings, we developed Fawkes, a testing framework to detect DDBs with recovered data state verification. It employs context-aware fault injection to target critical filesystem and kernel-level regions, functionality-guided fault triggering to explore untested paths, and checkpoint-based data graph verification to detect post-crash inconsistencies. We applied Fawkes to eight popular DBMSs and discovered 48 previously unknown DDBs, of which 16 have been fixed and 8 have been assigned CVE identifiers due to the severity.

• Security and privacy → Database and storage security.