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Bug #1261 ยป open-fault.c

Mathieu Desnoyers, 02/12/2021 09:52 AM

 
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>
#include <syscall.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdio.h>
#include <error.h>
#include <stdlib.h>
#include <string.h>

#define NAME_FILE "/tmp/filefile1"
#define PATH_STR "/tmp/filefile2"

int main()
{
int ret;
int fd;
char *name;
ssize_t len;

fd = open(NAME_FILE, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR,
0700);
if (fd < 0) {
perror("open1");
abort();
}
len = write(fd, PATH_STR, strlen(PATH_STR) + 1);
if (len < strlen(PATH_STR) + 1) {
abort();
}
/* mmap the name file which will be used as input string for openat
* filename parameter, triggering a page fault because the pages of this
* mapping are not populated in the page cache.
*/
name = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
if (name == MAP_FAILED) {
perror("mmap");
abort();
}
openat(42, name, 0, 0);
}

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