efficios / Memleak Finder

Memleak finder Mathieu Desnoyers, May 2013

• memleak-finder.so

example usage: LD_PRELOAD=<path_to>/memleak-finder.so appname

If you get e.g.:

[warning] trying to free unallocated ptr 0x18b2a70 caller 0x7fae7943dd57 or [leak] ptr: 0x18b2350 size: 0x160 caller: 0x7fae7943e28f

If you need to see local symbols as well ("static" function), you will need to use gdb "disassemble 0x...". A trick to hook gdb on the program after the leak printout is to add an assert(0) at the end of the library destructor, and run the program after issuing ulimit -c unlimited to gather a core dump of the application. Don't forget to compile your program and libraries, and install the "-dbg" versions of the system libraries if you want the make sure gdb can lookup their local symbols.

You can set the MEMLEAK_FINDER_PRINT environment variable to make the shared object print every allocation/free on stderr.

• malloc-stats.so

LD_PRELOAD=<path_to>/malloc-stats.so appname

Then, kill with:

killall -SIGUSR2 appname

It will show the output of malloc_stats(3) on stderr of the application.

Example output:

Arena 0: system bytes = 135168 in use bytes = 19360 Total (incl. mmap): system bytes = 135168 in use bytes = 19360 max mmap regions = 0 max mmap bytes = 0

• Credits

The design of this library is inspired by this presentation:

"Tips of malloc & free" Tetsuyuki Kobayashi 2013.2.22 Embedded Linux Conference http://events.linuxfoundation.org/images/stories/slides/elc2013_kobayashi_malloc.pdf