Question

I am using c in linux, when i run main.c i get below error:

* glibc detected /asde/pasc/source/cl/weasdashanges/webasdnges: malloc():
memory corruption: 0x08069098 **

the backtrace from gdb is as follows: its pointing to function dblogin which is strange because i am pretty sure that should not be the problem because i never made changes there.

if ((login = dblogin()) == FAIL)        return 0;

and this code was working fine before the changes.

 (gdb) backtrace
    #0  0x0012d422 in __kernel_vsyscall ()
    #1  0x002f7651 in raise () from /lib/tls/i686/cmov/libc.so.6
    #2  0x002faa82 in abort () from /lib/tls/i686/cmov/libc.so.6
    #3  0x0032e49d in ?? () from /lib/tls/i686/cmov/libc.so.6
    #4  0x00338591 in ?? () from /lib/tls/i686/cmov/libc.so.6
     #5  0x0033b395 in ?? () from /lib/tls/i686/cmov/libc.so.6
     #6  0x0033c70b in calloc () from /lib/tls/i686/cmov/libc.so.6
     #7  0x001f9cd6 in ?? () from /usr/lib/libsybdb.so.5
     #8  0x001edd1a in dblogin () from /usr/lib/libsybdb.so.5
     #9  0x0804de13 in ?? ()
    #10 0x0804e01b in ?? ()
     #11 0x0804bf9f in ?? ()
    #12 0x002e3bd6 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
    #13 0x0804a031 in ?? ()

Any ideas on how i can find out whats the specific problem? like a gdb command tells it to break on every write to that location

Answer 1

Use valgrind to find out memory leaks in your program. Also use more your debugger.

If you want to find out how is a particular location overwritten, you could use the watch command of gdb