Advanced driver code analysis techniques Tips and tricks to develop more secure & reliable drivers

1. HW-889P Advanced driver code analysis techniquesTips and tricks to develop more secure & reliable drivers Dave Sielaff Principal Software Development Engineer Microsoft Corporation

2. Motivation • Customers want reliable products • Some bugs are tough to find by debugging • Finding potential crashes earlier is always good

3. Agenda • Introducing the Source Code Annotation Language (SAL) • Understanding Visual Studio Code Analysis warnings • Adding SAL to existing driver Afterwards, you will have examples of how to • Fix bugs using Code Analysis warnings • Annotate parameters and shared variable access

4. Introducing SAL • Microsoft Source Code Annotation Language • Describes important aspects of code intent • Like using ASSERT on function declarations • Readable by humans and tools • Declaring locking behavior • Finding potential race conditions, deadlocks • Describing parameter behavior • Finding potential null dereferences, uninitialized memory use

5. Describing locking behavior • Which functions acquire/release locks? • _Acquires_lock_(lock) • _Releases_lock_(lock) • Does a function depend on a lock being held prior to call? • _Requires_lock_held_(lock) • Which variables are guarded by which lock? • _Guarded_by_(lock)

6. demo Concurrency Annotation Usage

7. Basic SAL parameter concepts • Input • Data is passed to called function, treated as read-only • Input/Output • Data is passed into function and potentially modified • Output • Caller only provides space for called function to write to • Called function writes data into that space • Output Pointers • Like Output, where value returned by called function is pointer

8. Basic SAL parameter concepts (continued) • Required • Pointer parameter that must be non-NULL • Optional • Pointer parameter that can be NULL

9. Basic SAL parameter table

10. demo Parameter Annotation Usage

11. Recap

12. Using Code Analysis and SAL • Code Analysis can find valuable bugs right out of the box • Adding SAL to your code makes Code Analysis even more effective • Think of SAL as compile-time ASSERT system • No need to annotate your code all at once • Annotating incrementally gets you incremental value, immediately and over time as your code evolves

13. For more information RELATED SESSIONS DOCUMENTATION & ARTICLES • TOOL-100T: Improving software quality using Visual Studio 11 C++ Code Analysis • Driver Development Tools • Windows Hardware DevCenter • Windows DevCenter • Visual Studio Code Analysis and SAL

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