tun: freebsd: avoid OOB writes

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2021-04-19 15:10:23 -06:00
parent 0687dc06c8
commit 3625f8d284

View file

@ -8,6 +8,7 @@ package tun
import (
"errors"
"fmt"
"io"
"net"
"os"
"sync"
@ -347,7 +348,13 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
}
func (tun *NativeTun) Write(buf []byte, offset int) (int, error) {
if offset < 4 {
return 0, io.ErrShortBuffer
}
buf = buf[offset-4:]
if len(buf) < 5 {
return 0, io.ErrShortBuffer
}
buf[0] = 0x00
buf[1] = 0x00
buf[2] = 0x00