Segmentation fault need help

Hi,

I am trying to run a program except I get the following segmentation fault.
I don't know how to solve it. Please if you know could you please help.

Thanks, Marcia



Program received signal SIGSEGV, Segmentation fault.

0x0a6e6962 in ?? ()

(gdb) bt

#0 0x0a6e6962 in ?? ()

Cannot access memory at address 0xa6d6461

(gdb)

"Marcia Hon" <honm@rogers.com> writes:

> Hi,
>
> I am trying to run a program except I get the following segmentation fault.
> I don't know how to solve it. Please if you know could you please help.
>
> Thanks, Marcia
>
> Program received signal SIGSEGV, Segmentation fault.
>
> 0x0a6e6962 in ?? ()
>
> (gdb) bt
>
> #0 0x0a6e6962 in ?? ()
>
> Cannot access memory at address 0xa6d6461

You have a corrupted stack. Look for buffer overflows in
automatically allocated memory. Another typical cause is freeing
automatic memory. It could also be caused by using an uninitialized
pointer. A memory debugger like Electric Fence or (for PC) valgrind
is useful for finding such bugs.

--
Måns Rullgård
mru@kth.se

Thanks.

I don't know how to solve it your way. I would like to learn. I, however,
solved it by sequentially putting printfs throughout the program!

Thanks again for your help.
Marcia

mru@kth.se (Måns Rullgård) writes:

> "Marcia Hon" <honm@rogers.com> writes:

> > (gdb) bt
> > #0 0x0a6e6962 in ?? ()

Note that this is ASCII: "\nnib", doing "x/s $esp" may reveal the
rest of the string which overflowed its buffer.

> You have a corrupted stack.

Most definitely.

> Look for buffer overflows in automatically allocated memory.

Yes. I would bet 10:1 that this is a simple strcpy() into an
automatic char array that is too small.

> Another typical cause is freeing automatic memory.

That would cause a SIGSEGV *in* malloc/free, not a jump to ASCII.

> It could also be caused by using an uninitialized pointer.

Or it could be that.

> A memory debugger like Electric Fence or (for PC) valgrind
> is useful for finding such bugs.

EFence will not help with this kind of bug at all, valgrind might
(if this is an uninitialized pointer, but not otherwize).

Cheers,
--
In order to understand recursion you must first understand recursion.
Remove /-nsp/ for email.

Marcia Hon wrote:
>
> I am trying to run a program except I get the following segmentation fault.
> I don't know how to solve it. Please if you know could you please help.

You are getting out of hand. Please STOP the excessive
cross-posting, and STOP posting OT matter, and START posting
cut-down compilable complete programs not exceeding 100 lines when
you need help. Failing this I suggest wholesale PLONKING, after
which you will not be able to get help anywhere.

For you, anything over one newsgroup is excessive crossposting.

--
Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net> USE worldnet address!