5cf23c53b8
* test/skodic.c (main): Don't use MAP_FIXED since valid virtual addresses vary between architectures (as far as I can tell the use of MAP_FIXED is not relevant to the test). Also don't assume the file desriptor returned by open call is 3 when passing it to mmap. Signed-off-by: James Hogan <james.hogan@imgtec.com>
38 lines
771 B
C
38 lines
771 B
C
/* This demonstrates races: kernel may actually open other file then
|
|
* you read at strace output. Create /tmp/delme with 10K of zeros and
|
|
* 666 mode, then run this under strace. If you see open successfull
|
|
* open of /etc/shadow, you know you've seen a race.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
char *c;
|
|
int fd;
|
|
|
|
fd = open("/tmp/delme", O_RDWR);
|
|
c = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
|
|
*c = 0;
|
|
|
|
if (fork()) {
|
|
while (1) {
|
|
strcpy(c, "/etc/passwd");
|
|
strcpy(c, "/etc/shadow");
|
|
}
|
|
} else {
|
|
while (1)
|
|
if ((fd = open(c, 0)) != -1)
|
|
close(fd);
|
|
}
|
|
|
|
return 0;
|
|
}
|