Custom memory allocator (malloc) implemented in C. salloc - secure allocator :)
A "Segregated Bins" allocator that uses a free list to manage allocated memory chunks. The bins are organized by size classes, each containing a list of free aligned memory chunks, assuring O(1) allocation complexity (At least in the average case) The allocator uses a best-fit strategy to find the best chunk for allocation, and it splits larger chunks when necessary. When a chunk is freed, it is added back to the free list and is merged with adjacent free chunks if possible.
The allocator also includes a mutex lock to ensure thread safety during allocation and deallocation.
Heap Mitigations currently implemented:
- Safe Unlinking & Double Free: integrity checking of the free list pointers before unlinking to ensure they did not get altered, and checking if a chunk is already freed before adding it back to the free list, preventing double free vulnerabilities.
- Use-After-Free: overwrite freed chunks with garbage data to prevent use-after-free vulnerabilities.
- Heap Canaries ("Security Cookies"): canary value at the header of each chunk to detect buffer overflows. If the canary is altered, the allocator aborts the program. canary value is generated using a random number generator at the start of the program and is unique for each run.