C Malloc Protection Checker

First of all, if you wonder why it is important to protect your malloc calls, I suggest this medium article.

In this repo you will find a shell script and a malloc wrapper to check malloc protection in your programs.

This script allows you to test your program by deliberately causing the malloc function to fail (i.e. by returning NULL) after a certain number of calls defined by the "limit" variable. You can test the program in a loop from zero to the defined limit or use it in "oneshot" mode in order to fail at exactly the defined number of calls.

:warning: If you are on a GNU/Linux system, you have to compile your project with CLANG compiler, not GCC compiler. Still for Linux, I advise you to compile your project with the -rdynamic CLANG flag in order to have the name of the calling function in the stacktrace and not just its address

Run:

• First, clone this repo.

• Compile your program as usual, without changing anything.

• Then, Run the script "malloc_checker.sh" with this usage:

  ./malloc_checker.sh bin={your_compiled_program} limit={malloc_limit} [loop={false|true}]"

  Here is the possible arguments:

  • bin: binary you want to test
  • limit: the number of calls to malloc that can succeed before malloc returns NULL
  • loop: [optional parameter] -> use if you want to loop from 0 to limit (default: false)"

  Here is an example to test malloc function failure in your compiled program 'test' after first call, until 20th call

  ./malloc_checker.sh bin=./test limit=20 loop=true

  Note that if you want to run your program with arguments: just enclose the whole thing in quotes like this:

  ./malloc_checker.sh bin="./test ARG1 ARG2 ARG3" limit=20 loop=true