On Fri, 2016-07-08 at 17:52 +0200, Michal Kubecek wrote: > If socket filter truncates an udp packet below the length of UDP header > in udpv6_queue_rcv_skb() or udp_queue_rcv_skb(), it will trigger a > BUG_ON in skb_pull_rcsum(). This BUG_ON (and therefore a system crash if > kernel is configured that way) can be easily enforced by an unprivileged > user which was reported as CVE-2016-6162. For a reproducer, see > http://seclists.org/oss-sec/2016/q3/8 > > Fixes: e6afc8ace6dd ("udp: remove headers from UDP packets before queueing") > Reported-by: Marco Grassi <marco....@gmail.com> > Signed-off-by: Michal Kubecek <mkube...@suse.cz> > --- > net/ipv4/udp.c | 2 ++ > net/ipv6/udp.c | 2 ++ > 2 files changed, 4 insertions(+) > > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c > index ca5e8ea29538..4aed8fc23d32 100644 > --- a/net/ipv4/udp.c > +++ b/net/ipv4/udp.c > @@ -1583,6 +1583,8 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff > *skb) > > if (sk_filter(sk, skb)) > goto drop; > + if (unlikely(skb->len < sizeof(struct udphdr))) > + goto drop; > > udp_csum_pull_header(skb); > if (sk_rcvqueues_full(sk, sk->sk_rcvbuf)) { > diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c > index 005dc82c2138..acc09705618b 100644 > --- a/net/ipv6/udp.c > +++ b/net/ipv6/udp.c > @@ -620,6 +620,8 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff > *skb) > > if (sk_filter(sk, skb)) > goto drop; > + if (unlikely(skb->len < sizeof(struct udphdr))) > + goto drop; > > udp_csum_pull_header(skb); > if (sk_rcvqueues_full(sk, sk->sk_rcvbuf)) {
Arg :( Acked-by: Eric Dumazet <eduma...@google.com> Thanks !