memexec.c

#define _GNU_SOURCE
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>

int main(int argc, char **argv) {
        int fd;
        if((fd = open("/bin/ls", O_RDONLY)) == -1) exit(1);
        off_t len = lseek(fd, 0, SEEK_END);
        lseek(fd, 0, SEEK_SET);
        unsigned char *buf = malloc(len);
        read(fd, buf, len);
        close(fd);
        int memfd;
        if((memfd = memfd_create("memls", MFD_CLOEXEC)) == -1) exit(2);
        write(memfd, buf, len);
        char *args[] = {"ls", "/", NULL};
        char *env[] = {NULL};
        fexecve(memfd, args, env);
        exit(3);
}