From d92a7db710c32db826a00ba9bc7a22e741d5041e Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 21 Aug 2007 00:06:37 -0700 Subject: [PATCH] [SNAP]: Check packet length before reading The snap_rcv code reads 5 bytes so we should make sure that we have 5 bytes in the head before proceeding. Based on diagnosis and fix by Evgeniy Polyakov, reported by Alan J. Wylie. Patch also kills the skb->sk assignment before kfree_skb since it's redundant. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- net/802/psnap.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/net/802/psnap.c b/net/802/psnap.c index 04ee43e753..31128cb92a 100644 --- a/net/802/psnap.c +++ b/net/802/psnap.c @@ -55,6 +55,9 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev, .type = __constant_htons(ETH_P_SNAP), }; + if (unlikely(!pskb_may_pull(skb, 5))) + goto drop; + rcu_read_lock(); proto = find_snap_client(skb_transport_header(skb)); if (proto) { @@ -62,14 +65,18 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev, skb->transport_header += 5; skb_pull_rcsum(skb, 5); rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev); - } else { - skb->sk = NULL; - kfree_skb(skb); - rc = 1; } - rcu_read_unlock(); + + if (unlikely(!proto)) + goto drop; + +out: return rc; + +drop: + kfree_skb(skb); + goto out; } /* -- 2.39.5