why does malloc call free?

[hendrik@topoi.pooq.com]

Not looking for you to analyse my debugging session (I'll
do that myself), but I'm really curious -- why does malloc call free?

Program received signal SIGSEGV, Segmentation fault.
0x00002aaaaac2faab in free () from /lib/libc.so.6
(gdb) bt
#0  0x00002aaaaac2faab in free () from /lib/libc.so.6
#1  0x00002aaaaac30cfb in malloc () from /lib/libc.so.6

-- hendrik