I installed current gcc-snapshot (and upgraded glibc) on otherwise
lenny system, even compiled with gcc-snapshot still runs fine:
Target: x86_64-linux-gnu
gcc version 4.4.0 20081023 (experimental) [trunk revision 141326] (Debian 20081023-1)
$ dpkg -l gcc-4.3 gcc-snapshot libc6
I tried as another user and failed to reproduce the problem.
That led me to discover an error: I meant to use "env --ignore" (-i, not -u),
and the real culprit, which may be a use of freed memory:
env -i -- /bin/zsh -f -c \
'ulimit -v 5000;MALLOC_PERTURB_=90 ./a.out %$[5*2**22]d'
The error is exposed only if you set MALLOC_PERTURB_ to a nonzero
value in your environment.