test/debug/buserr.c

   1 /*
   2  * Test a fork/munmap vm_object shadow chain race
   3  *
   4  * Written by "Samuel J. Greear" <sjg@evilcode.net>
   5  */
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <err.h>
   9 #include <sysexits.h>
  10 #include <unistd.h>
  11
  12 #include <sys/types.h>
  13 #include <sys/mman.h>
  14 #include <sys/param.h>
  15 #include <sys/wait.h>
  16
  17 #define MAPPING_PAGES   4096
  18
  19 int
  20 main(int argc, char *argv[])
  21 {
  22     unsigned int i, size;
  23     int status;
  24     pid_t pid;
  25     void *mapping;
  26     char tmp[100];
  27
  28     for (i = 1; i < MAPPING_PAGES; ++i) {
  29         size = PAGE_SIZE * i;
  30         mapping = mmap(0, size, PROT_READ|PROT_WRITE, MAP_ANON|MAP_SHARED,
  31                        -1, 0);
  32         if (mapping == MAP_FAILED)
  33             errx(EX_OSERR, "mmap() failed");
  34
  35         memset(mapping, 'x', 10);
  36         printf(" %d", i);
  37         fflush(stdout);
  38
  39         pid = fork();
  40         if (pid == 0) {
  41             memcpy(&tmp, mapping, 12);
  42             return (0);
  43         } else if (pid != -1) {
  44             if (munmap(mapping, PAGE_SIZE * i) != 0) {
  45                 printf("munmap failed\n");
  46                 return (0);
  47             }
  48             waitpid(pid, &status, 0);
  49             if (status == 10) {
  50                 printf("child sig10 at %d pages\n", i);
  51                 return (0);
  52             }
  53         } else {
  54             printf("fork failed\n");
  55         }
  56     }
  57
  58     return (0);
  59 }