Need more information about Aborted (core dumped)

c malloc runtime-error coredump backtrace
gangadhars picture gangadhars · Nov 27, 2013 · Viewed 60.5k times · Source

This bellow code will generate Aborted (core dumped) at last line.

code:

  #include <stdio.h>
  #include <malloc.h>

  int main()
  {
    char *ptr;
    ptr=malloc(sizeof(char)*10);
    free(ptr);
    free(ptr);     // core dumped
  }

output is:

*** glibc detected *** ./a.out: double free or corruption (fasttop): 0x091f7008 ***
======= Backtrace: =========
/lib/i386-linux-gnu/libc.so.6(+0x75ee2)[0xb7665ee2]
./a.out[0x804846d]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb76094d3]
./a.out[0x8048371]
======= Memory map: ========
08048000-08049000 r-xp 00000000 fc:00 4070236    /home/gangadhar/a.out
08049000-0804a000 r--p 00000000 fc:00 4070236    /home/gangadhar/a.out
0804a000-0804b000 rw-p 00001000 fc:00 4070236    /home/gangadhar/a.out
091f7000-09218000 rw-p 00000000 00:00 0          [heap]
b75ba000-b75d6000 r-xp 00000000 fc:00 22938319   /lib/i386-linux-gnu/libgcc_s.so.1
b75d6000-b75d7000 r--p 0001b000 fc:00 22938319   /lib/i386-linux-gnu/libgcc_s.so.1
b75d7000-b75d8000 rw-p 0001c000 fc:00 22938319   /lib/i386-linux-gnu/libgcc_s.so.1
b75ef000-b75f0000 rw-p 00000000 00:00 0 
b75f0000-b7794000 r-xp 00000000 fc:00 22937623   /lib/i386-linux-gnu/libc-2.15.so
b7794000-b7795000 ---p 001a4000 fc:00 22937623   /lib/i386-linux-gnu/libc-2.15.so
b7795000-b7797000 r--p 001a4000 fc:00 22937623   /lib/i386-linux-gnu/libc-2.15.so
b7797000-b7798000 rw-p 001a6000 fc:00 22937623   /lib/i386-linux-gnu/libc-2.15.so
b7798000-b779b000 rw-p 00000000 00:00 0 
b77b1000-b77b4000 rw-p 00000000 00:00 0 
b77b4000-b77b5000 r-xp 00000000 00:00 0          [vdso]
b77b5000-b77d5000 r-xp 00000000 fc:00 22937715   /lib/i386-linux-gnu/ld-2.15.so
b77d5000-b77d6000 r--p 0001f000 fc:00 22937715   /lib/i386-linux-gnu/ld-2.15.so
b77d6000-b77d7000 rw-p 00020000 fc:00 22937715   /lib/i386-linux-gnu/ld-2.15.so
bf7e0000-bf801000 rw-p 00000000 00:00 0          [stack]
Aborted (core dumped)

Here I'm interested to know in which cases these core dumped will occur?

Can we find out at which line this is occurred without using debugger?

what information it is showing(about shared libraries)?

Answer

Chinna picture Chinna · Nov 27, 2013

Core dump file generally gets created when a program terminates abnormally. Calling free() twice on a pointer causes segmentation fault. That's why you are getting coredumped. You can find some information here about calling free on same pointer twice.

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