ocalbox root $ cat a.s
.global _start

_start:
subl %eax,%eax
incb %al
int $0x80
localbox root $ cat a.c
char sc[] =
                                      // <_start>
        "\x29\xc0"                    // sub    %eax,%eax
        "\xfe\xc0"                    // inc    %al
        "\xcd\x80"                    // int    $0x80
;

int main()
{
        void    (*fp)(void) = (void (*)(void))sc;

        printf("Length: %d\n",strlen(sc));
        fp();
}


localbox root $ strace ./a
execve("./a", ["./a"], [/* 43 vars */]) = 0
uname({sys="Linux", node="localbox", ...}) = 0
brk(0)                                  = 0x804a000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=87989, ...}) = 0
mmap2(NULL, 87989, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f00000
close(3)                                = 0
open("/lib/tls/libc.so.6", O_RDONLY)    = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20O\1\000"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1441261, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7eff000
mmap2(NULL, 1240284, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7dd0000
mmap2(0xb7ef9000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x128) = 0xb7ef9000
mmap2(0xb7efd000, 7388, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7efd000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7dcf000
mprotect(0xb7ef9000, 4096, PROT_READ)   = 0
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7dcf6c0, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
munmap(0xb7f00000, 87989)               = 0
fstat64(1, {st_mode=S_IFCHR|0700, st_rdev=makedev(136, 0), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f15000
write(1, "Length: 6\n", 10Length: 6
)             = 10
_exit(-1209028612)                      = ?