From 2643c3ca60ad11981537c9cd7123fda2a3d26e7e Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 5 Feb 2009 15:05:45 -0800 Subject: [PATCH] udp: Fix UDP short packet false positive The UDP header pointer assignment must happen after calling pskb_may_pull(). As pskb_may_pull() can potentially alter the SKB buffer. This was exposted by running multicast traffic through the NIU driver, as it won't prepull the protocol headers into the linear area on receive. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- net/ipv4/udp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 1ab180bad72a1..cc3a0a06c004d 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1231,7 +1231,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, int proto) { struct sock *sk; - struct udphdr *uh = udp_hdr(skb); + struct udphdr *uh; unsigned short ulen; struct rtable *rt = (struct rtable*)skb->dst; __be32 saddr = ip_hdr(skb)->saddr; @@ -1244,6 +1244,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, if (!pskb_may_pull(skb, sizeof(struct udphdr))) goto drop; /* No space for header. */ + uh = udp_hdr(skb); ulen = ntohs(uh->len); if (ulen > skb->len) goto short_packet; -- 2.39.5