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/*
* Copyright (c) 2018 Todd Mortimer <mortimer@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/mman.h>
#include "../pivot.h"
static size_t *realstack;
static char *scan;
static size_t scansize = UINT16_MAX;
/* scan some memory crossing a page boundary */
size_t dowork() {
size_t b = 0;
size_t i;
for (i = 0; i < scansize; ++i)
b += *scan++;
// We should be killed before we get here
pivot(realstack);
return b;
}
void doexit() {
_exit(0);
}
int main() {
/* allocate some memory to scan */
scan = mmap(NULL, scansize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
/* set up a rop chain on the real stack for syscalls */
size_t stack[10];
stack[0] = (size_t)doexit;
realstack = stack;
/* set up a basic alt stack on the heap that does some work */
size_t *newstack = calloc(10, sizeof(size_t));
printf("non-MAP_STACK stack at %p\n", newstack);
newstack[0] = (size_t)dowork;
pivot(newstack);
return 0;
}
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