tests/vla_test.c

   1 /*
   2  * Test that allocating a variable length array in a loop
   3  * does not use up a linear amount of memory
   4  */
   5
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 #include <string.h>
   9
  10 #define LOOP_COUNT 1000
  11 #define ARRAY_SIZE 100
  12
  13 /* Overwrite a VLA. This will overwrite the return address if SP is incorrect */
  14 void smash(char *p, int n) {
  15   memset(p, 0, n);
  16 }
  17
  18 int test1(int n) {
  19   int i;
  20   char *array_ptrs[LOOP_COUNT];
  21
  22   for (i = 0; i < LOOP_COUNT; ++i) {
  23     char test[n];
  24     smash(test, n);
  25     array_ptrs[i] = test;
  26   }
  27
  28   return (array_ptrs[0]-array_ptrs[LOOP_COUNT-1] < n) ? 0 : 1;
  29 }
  30
  31 /* ensure goto does not circumvent array free */
  32 int test2(int n) {
  33   char *array_ptrs[LOOP_COUNT];
  34
  35   int i = 0;
  36 loop:;
  37   char test[n];
  38   smash(test, n);
  39   if (i >= LOOP_COUNT)
  40     goto end;
  41   array_ptrs[i] = test;
  42   ++i;
  43   goto loop;
  44
  45 end:
  46   smash(test, n);
  47   char test2[n];
  48   smash(test2, n);
  49   return (array_ptrs[0] - array_ptrs[LOOP_COUNT-1] < n) ? 0 : 1;
  50 }
  51
  52 int test3(int n) {
  53   char test[n];
  54   smash(test, n);
  55   goto label;
  56 label:
  57   smash(test, n);
  58   char test2[n];
  59   smash(test2, n);
  60   return (test-test2 >= n) ? 0 : 1;
  61 }
  62
  63 #define RUN_TEST(t) \
  64   if (!testname || (strcmp(#t, testname) == 0)) { \
  65     fputs(#t "... ", stdout); \
  66     fflush(stdout); \
  67     if (t(ARRAY_SIZE) == 0) { \
  68       fputs("success\n", stdout); \
  69     } else { \
  70       fputs("failure\n", stdout); \
  71       retval = EXIT_FAILURE; \
  72     } \
  73   }
  74
  75 int main(int argc, char **argv) {
  76   const char *testname = NULL;
  77   int retval = EXIT_SUCCESS;
  78   if (argc > 1)
  79     testname = argv[1];
  80   RUN_TEST(test1)
  81   RUN_TEST(test2)
  82   RUN_TEST(test3)
  83   return retval;
  84 }