Unchecked Return Value of Malloc Detection

Detection Workflow

1. Identify allocation operations: Find all malloc() calls, locate calloc() calls, identify realloc() calls, map new/delete operations
2. Trace return values: Follow allocation result, identify first dereference, check for NULL validation, assess error handling
3. Check error handling: Verify NULL checks exist, assess error handling completeness, review fallback behavior, check for graceful degradation
4. Assess impact: Can allocation fail? What happens on failure? Is crash possible? What's the security impact?

Key Patterns

• Unchecked malloc: malloc() return value not checked, direct use of malloc() result, no NULL check before dereference, assumption malloc never fails
• Unchecked calloc: calloc() return value not checked, direct use of calloc() result, no NULL check before dereference, assumption calloc never fails
• Unchecked realloc: realloc() return value not checked, direct assignment to original pointer, no NULL check before dereference, losing original pointer on failure
• Unchecked new (C++): new return value not checked, assuming new never throws, no exception handling, missing std::nothrow usage

Output Format

Report with: id, type, subtype, severity, confidence, location, vulnerability, allocation_call, allocation_type, allocation_size, null_check, first_dereference, exploitable, attack_scenario, impact, mitigation.

Severity Guidelines

• HIGH: Unchecked allocation in critical code
• MEDIUM: Unchecked allocation causing crashes
• LOW: Unchecked allocation with limited impact

See Also

• patterns.md

  - Detailed detection patterns and exploitation scenarios

• examples.md

  - Example analysis cases and code samples

• references.md

  - CWE references and mitigation strategies