Diving into glibc heap

In this section, implementation of glibc’s heap management functions will be discussed in depth. The analysis was done on glibc’s source code dated 27th March 2017. The source is very well documented.

Apart from the source code, the matter presented is influenced by:

• Understanding glibc malloc
• Understanding the heap by breaking it

Before moving into the implementation, it is important to keep the following notes in mind:

1. Instead of size_t, INTERNAL_SIZE_T is used internally (which by default is equal to size_t).

2. Alignment is defined as 2 * (sizeof(size_t)).

3. MORECORE is defined as the routine to call to obtain more memory. By default it is defined as sbrk.

Next, we shall study the different data types used internally, bins, chunks, and internals of the different functions used.

Additional Resources

1. r2Con2016 Glibc Heap Analysis with radare2 video