Dump of assembler code for function main:
   0x0804865d <+0>:     lea    0x4(%esp),%ecx
   0x08048661 <+4>:     and    $0xfffffff0,%esp
   0x08048664 <+7>:     pushl  -0x4(%ecx)
   0x08048667 <+10>:    push   %ebp
   0x08048668 <+11>:    mov    %esp,%ebp
   0x0804866a <+13>:    push   %ecx
   0x0804866b <+14>:    sub    $0x14,%esp
   0x0804866e <+17>:    mov    0x804a03c,%eax
   0x08048673 <+22>:    push   $0x0
   0x08048675 <+24>:    push   $0x2
   0x08048677 <+26>:    push   $0x0
   0x08048679 <+28>:    push   %eax
   0x0804867a <+29>:    call   0x8048490 <setvbuf@plt>
   0x0804867f <+34>:    add    $0x10,%esp
   0x08048682 <+37>:    call   0x8048450 <getegid@plt>
   0x08048687 <+42>:    mov    %eax,-0xc(%ebp)
   0x0804868a <+45>:    sub    $0x4,%esp
   0x0804868d <+48>:    pushl  -0xc(%ebp)
   0x08048690 <+51>:    pushl  -0xc(%ebp)
   0x08048693 <+54>:    pushl  -0xc(%ebp)
   0x08048696 <+57>:    call   0x80484b0 <setresgid@plt>
   0x0804869b <+62>:    add    $0x10,%esp
   0x0804869e <+65>:    sub    $0xc,%esp
   0x080486a1 <+68>:    push   $0x8048810
   0x080486a6 <+73>:    call   0x8048460 <puts@plt>
   0x080486ab <+78>:    add    $0x10,%esp
   0x080486ae <+81>:    call   0x804862f <vuln>
   0x080486b3 <+86>:    mov    $0x0,%eax
   0x080486b8 <+91>:    mov    -0x4(%ebp),%ecx
   0x080486bb <+94>:    leave
   0x080486bc <+95>:    lea    -0x4(%ecx),%esp

(gdb) c
Continuing.
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Breakpoint 5, 0x080486ab in main ()