diff options
| -rw-r--r-- | drivers/net/ppp_generic.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index 10e5d985afa3..edfa15d2e795 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -1465,7 +1465,12 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb) continue; } - mtu = pch->chan->mtu - hdrlen; + /* + * hdrlen includes the 2-byte PPP protocol field, but the + * MTU counts only the payload excluding the protocol field. + * (RFC1661 Section 2) + */ + mtu = pch->chan->mtu - (hdrlen - 2); if (mtu < 4) mtu = 4; if (flen > mtu) |