test_write.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
                 
int main(int argc, char **argv) {
    unsigned char data[258];
    unsigned char data2[258];
    strcpy(data, "averylongstringwithnotmuchmeaningaverylongstringwithnotmuchmeaning"
                 "averylongstringwithnotmuchmeaningaverylongstringwithnotmuchmeaning"
                 "averylongstringwithnotmuchmeaningaverylongstringwithnotmuchmeaning");
    printf("data = %p\n", data);
    // Uncommenting these two lines will cause PANDA to see the writes in __copy_from_user_ll_nozero
    //printf("data2 = %p\n", data2);
    //memcpy(data2,data,258);
    int fd = open("foo", O_CREAT|O_RDWR, 0644);
    int n = write(fd, data, 258);
    fsync(fd);
    close(fd);
    return 0;
}