http://udrepper.livejournal.com/11429.html
If you set MALLOC_PERTURB_=$NUMBER, it sets all malloc'ed bytes to $NUMBER, and the bitwise inverse upon free. It is great to expose otherwise difficult to detect bugs, at the expense of speed. It might also be useful for /dev/ksm.
Posted Nov 13, 2008 19:52 UTC (Thu) by nix (subscriber, #2304)
[Link]
It's a really cool feaure, but, well, Ulrich says that it 'Seems like the
number of people who know this feature is still almost zero'. Yes, that's
because it was never documented, as with pretty much everything glibc can
do above POSIX. (e.g., quick, how does LD_AUDIT work? How do you use it?
Good luck finding out without reading the source, and it's tricky to
understand even then.)