From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 2/2] netfilter: nf_reject_ipv4: Fix use-after-free in send_reset Date: Wed, 1 Nov 2017 19:48:12 +0100 Message-ID: <20171101184812.4813-3-pablo@netfilter.org> References: <20171101184812.4813-1-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <20171101184812.4813-1-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Tejaswi Tanikella niph is not updated after pskb_expand_head changes the skb head. It still points to the freed data, which is then used to update tot_len and checksum. This could cause use-after-free poison crash. Update niph, if ip_route_me_harder does not fail. This only affects the interaction with REJECT targets and br_netfilter. Signed-off-by: Tejaswi Tanikella Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/nf_reject_ipv4.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index eeacbdaf7cdf..5cd06ba3535d 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -132,6 +132,8 @@ void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook) if (ip_route_me_harder(net, nskb, RTN_UNSPEC)) goto free_nskb; + niph = ip_hdr(nskb); + /* "Never happens" */ if (nskb->len > dst_mtu(skb_dst(nskb))) goto free_nskb; -- 2.11.0