Liu Qishuai reported a stack overflow in libgtop2 in Launchpad:

https://launchpad.net/bugs/79206

I could reproduce it on Ubuntu feisty on AMD64.
libgtop2 is 2.14.5-0ubuntu1.

Steps to reproduce:
 export dir=$(perl -e " print 's/'x1000;")
 mkdir -p $dir
 cp /bin/sleep $dir
 $dir/sleep 100 &
 gnome-system-monitor

gnome-system-monitor aborts with
*** stack smashing detected ***: gnome-system-monitor terminated
Aborted

A backtrace leads to
(gdb) frame 4

+ Trace 102063

I've started to look for the problem:

The problematic code is in sysdeps/linux/procmap.c: glibtop_get_proc_map_s()

155 char line[1024];
[...]
164 char filename [GLIBTOP_MAP_FILENAME_LEN+1];
165
166 glibtop_map_entry *entry;
167
168 if (!fgets(line, sizeof line, maps))
169 break;
170
171 /* 8 arguments */
172 rv = sscanf(line, PROC_MAPS_FORMAT,
173 &start, &end, flags, &offset,
174 &dev_major, &dev_minor, &inode, filename);

GLIBTOP_MAP_FILENAME_LEN is 215 (include/glibtop/procmap.h)
PROC_MAPS_FORMAT is defined as "%16llx-%16llx %4c %16llx %02hx:%02hx %llu%*[ ]%[^\n]\n"

maps is /proc/<pid>/smaps and the first line looks in this case like
00400000-00404000 r-xp 00000000 08:07 1849138 /home/michael/tmp/s/s/s/s/s/s/s/s/s/s/s/s/s/s/s/s/s/s/s/[...]

After the sscanf 'filename' contains the filename which is much longer than the char array and overflows into the stack.