~jkaivo/mapalloc

ref: 83e70e1b6c7abd0315dd8cd5a98a91c58e0cd8bd mapalloc/README.md -rw-r--r-- 1.7 KiB
83e70e1b — Jakob Kaivo munmap() extra pages during realloc() 2 years ago

#MapAlloc

MapAlloc is a memory mapping based allocator with an API compatible with the C <stdlib.h> dynamic memory functions. By using memory mappings for each allocation, MapAlloc is able to provide guard pages to detect heap overflow and underflow, as well as potentially identifying use-after-free or double-free errors (in all cases, your program will crash, which is preferable to being silently exploited).

MapAlloc also maintains metadata independently from the heap, so it eliminates an entire class of vulnerabilities which rely on easy access to this metadata.

#Building

Just run make. This will give you libmapalloc.a, which you can statically link into your own programs, as well as libwrapalloc.so, which can be used with LD_PRELOAD to override your standard C library's dynamic memory functions.

#Including in your program

In your source file:

#include "mapalloc.h"

This will give you:

void *MA_malloc(size_t n);
void *MA_calloc(size_t nelem, size_t elsize);
void *MA_realloc(void *ptr, size_t n);
void MA_free(void *ptr);

Or, you can ask for macros to provide the same interfaces as <stdlib.h> (note that if you need to also include <stdlib.h>, you should include it before "mapalloc.h"):

#define MA_OVERRIDE_STDLIB
#include "mapalloc.h"

This will give you access to the same set of functions as above, but also provide macros:

#define malloc(n)	MA_malloc(n)
#define calloc(n, e)	MA_calloc(n, e)
#define realloc(p, n)	MA_realloc(p, n)
#define free(p)		MA_free(p)

Link your program with -lmapalloc (you may also need to specify -L with the path to where libmapalloc.a is if you don't copy it to part of your linker's default search path).