From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] arp: fix possible crash in arp_rcv() Date: Fri, 08 Feb 2013 20:48:21 -0800 Message-ID: <1360385301.6696.11.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev To: David Miller Return-path: Received: from mail-da0-f49.google.com ([209.85.210.49]:53017 "EHLO mail-da0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760649Ab3BIEsY (ORCPT ); Fri, 8 Feb 2013 23:48:24 -0500 Received: by mail-da0-f49.google.com with SMTP id t11so2087221daj.8 for ; Fri, 08 Feb 2013 20:48:24 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet We should call skb_share_check() before pskb_may_pull(), or we can crash in pskb_expand_head() Signed-off-by: Eric Dumazet --- net/ipv4/arp.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 9547a273..ded146b 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -928,24 +928,25 @@ static void parp_redo(struct sk_buff *skb) static int arp_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) { - struct arphdr *arp; + const struct arphdr *arp; + + if (dev->flags & IFF_NOARP || + skb->pkt_type == PACKET_OTHERHOST || + skb->pkt_type == PACKET_LOOPBACK) + goto freeskb; + + skb = skb_share_check(skb, GFP_ATOMIC); + if (!skb) + goto out_of_mem; /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ if (!pskb_may_pull(skb, arp_hdr_len(dev))) goto freeskb; arp = arp_hdr(skb); - if (arp->ar_hln != dev->addr_len || - dev->flags & IFF_NOARP || - skb->pkt_type == PACKET_OTHERHOST || - skb->pkt_type == PACKET_LOOPBACK || - arp->ar_pln != 4) + if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) goto freeskb; - skb = skb_share_check(skb, GFP_ATOMIC); - if (skb == NULL) - goto out_of_mem; - memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);