exp-sgcheck/tests/stackerr.c

   1
   2 /* Check basic stack overflow detection.
   3
   4    It's difficult to get consistent behaviour across all platforms.
   5    For example, x86 w/ gcc-4.3.1 gives
   6
   7      Expected: stack array "a" in frame 2 back from here
   8      Actual:   stack array "beforea" in frame 2 back from here
   9
  10    whereas amd64 w/ gcc-4.3.1 gives
  11
  12      Expected: stack array "a" in frame 2 back from here
  13      Actual:   unknown
  14
  15    This happens because on x86 the arrays are placed on the
  16    stack without holes in between, but not so for amd64.  I don't
  17    know why.
  18 */
  19
  20
  21 #include <stdio.h>
  22
  23 __attribute__((noinline)) void foo ( long* sa, int n )
  24 {
  25   int i;
  26   for (i = 0; i < n; i++)
  27     sa[i] = 0;
  28 }
  29
  30 __attribute__((noinline)) void bar ( long* sa, int n )
  31 {
  32    foo(sa, n);
  33 }
  34
  35 int main ( void )
  36 {
  37   int i;
  38   long beforea[3];
  39   long a[7];
  40   long aftera[3];
  41   bar(a, 7+1);     /* generates error */
  42   bar(a, 7+0);     /* generates no error */
  43   for (i = 0; i < 7+1; i++) {
  44      a[i] = 0;
  45   }
  46  {char beforebuf[8];
  47   char buf[8];
  48   char afterbuf[8];
  49   sprintf(buf, "%d", 123456789);
  50   return 1 & ((a[4] + beforea[1] + aftera[1] + beforebuf[1]
  51                     + buf[2] + afterbuf[3]) / 100000) ;
  52  }
  53 }