root@ubuntu:~# gdb -q /usr/sbin/proftpd `pidof proftpd`
Reading symbols from /usr/sbin/proftpd...(no debugging symbols found)...done.
Attaching to program: /usr/sbin/proftpd, process 2042
Reading symbols from /lib/libacl.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libacl.so.1
Reading symbols from /lib/libattr.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libattr.so.1
Reading symbols from /lib/libssl.so.0.9.8...(no debugging symbols found)...done.
Loaded symbols for /lib/libssl.so.0.9.8
Reading symbols from /lib/libcrypto.so.0.9.8...(no debugging symbols found)...done.
Loaded symbols for /lib/libcrypto.so.0.9.8
Reading symbols from /lib/libcap.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libcap.so.2
Reading symbols from /lib/libpam.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libpam.so.0
Reading symbols from /lib/libcrypt.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libz.so.1
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/libnss_files.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_files.so.2
Reading symbols from /usr/lib/proftpd/mod_ctrls_admin.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_ctrls_admin.so
Reading symbols from /usr/lib/proftpd/mod_tls.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_tls.so
Reading symbols from /usr/lib/proftpd/mod_radius.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_radius.so
Reading symbols from /usr/lib/proftpd/mod_quotatab.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_quotatab.so
Reading symbols from /usr/lib/proftpd/mod_quotatab_file.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_quotatab_file.so
Reading symbols from /usr/lib/proftpd/mod_quotatab_radius.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_quotatab_radius.so
Reading symbols from /usr/lib/proftpd/mod_wrap.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_wrap.so
Reading symbols from /lib/libwrap.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libwrap.so.0
Reading symbols from /lib/libnsl.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /usr/lib/proftpd/mod_rewrite.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_rewrite.so
Reading symbols from /usr/lib/proftpd/mod_load.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_load.so
Reading symbols from /usr/lib/proftpd/mod_ban.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_ban.so
Reading symbols from /usr/lib/proftpd/mod_wrap2.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_wrap2.so
Reading symbols from /usr/lib/proftpd/mod_wrap2_file.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_wrap2_file.so
Reading symbols from /usr/lib/proftpd/mod_dynmasq.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_dynmasq.so
Reading symbols from /usr/lib/proftpd/mod_vroot.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_vroot.so
Reading symbols from /usr/lib/proftpd/mod_ifsession.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/proftpd/mod_ifsession.so
Reading symbols from /lib/libnss_compat.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_compat.so.2
Reading symbols from /lib/libnss_nis.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_nis.so.2
0x002a8416 in __kernel_vsyscall ()
(gdb) set follow-fork-mode child
(gdb) continue
Continuing.
[New process 2063]

Program received signal SIGSEGV, Segmentation fault.
[Switching to process 2063]
0x0031d7cf in ?? () from /lib/libc.so.6
(gdb) info registers
eax            0x41414141	1094795585
ecx            0xbfc53bfc	-1077593092
edx            0x1	1
ebx            0x402ff4	4206580
esp            0xbfc5365c	0xbfc5365c
ebp            0xbfc53be4	0xbfc53be4
esi            0x3e13a6	4068262
edi            0x41414141	1094795585
eip            0x31d7cf	0x31d7cf
eflags         0x10202	[ IF RF ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x33	51
(gdb) back
#0  0x0031d7cf in ?? () from /lib/libc.so.6
#1  0x0030b19c in ?? () from /lib/libc.so.6
#2  0x0038e980 in __fortify_fail () from /lib/libc.so.6
#3  0x0038e92a in __stack_chk_fail () from /lib/libc.so.6
#4  0x0805b4f0 in pr_cmd_read ()
#5  0xfff0fff0 in ?? ()
#6  0xfff0fff0 in ?? ()
#7  0xfff0fff0 in ?? ()
#8  0xfff0fff0 in ?? ()
#9  0xfff0fff0 in ?? ()
#10 0xfff0fff0 in ?? ()
#11 0xfff0fff0 in ?? ()
#12 0xfff0fff0 in ?? ()
#13 0x0825cb9c in ?? ()
Cannot access memory at address 0xfff0fff4
(gdb)