Re: Stack protection via GCC's `-fstack-protector'

[Thomas Schwinge]

Hello!

On Wed, Nov 08, 2006 at 11:14:19PM +0100, Samuel Thibault wrote:
> Thomas Schwinge, le Wed 08 Nov 2006 22:40:54 +0100, a ?crit :
> > Is it feasible to have the `-fstack-protector' functionality in GNU Mach
> > and GRUB2 (and how to do that, then) or shall we unconditionally pass
> > `-fno-stack-protector' if available?
> 
> I'd say it shouldn't be very hard to provide a stack_chk_fail function,
> even if all it does is just panic().

Having had a look at glibc's implementation and its complexity ;-) that
might indeed be a reachable goal (assuming that no other surprises show
up):

debug/stack_chk_fail.c
#v+
[Copyright header.]

#include <stdio.h>
#include <stdlib.h>


extern char **__libc_argv attribute_hidden;

void
__attribute__ ((noreturn))
__stack_chk_fail (void)
{
  /* The loop is added only to keep gcc happy.  */
  while (1)
    __libc_message (1, "*** stack smashing detected ***: %s terminated\n",
                    __libc_argv[0] ?: "<unknown>");
}
#v-


I'll give it a try.


Regards,
 Thomas

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