From: Jiri Benc <jbenc@redhat.com>
Date: Thu, 7 Nov 2013 18:59:19 +0000 (+0100)
Subject: nfnetlink: do not ack malformed messages
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cdbe7c2d6d485459801838c244c409b938e32df5;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

nfnetlink: do not ack malformed messages

Commit 0628b123c96d ("netfilter: nfnetlink: add batch support and use it
from nf_tables") introduced a bug leading to various crashes in netlink_ack
when netlink message with invalid nlmsg_len was sent by an unprivileged
user.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 027f16af51a0..046aa13b4fea 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -363,13 +363,15 @@ static void nfnetlink_rcv(struct sk_buff *skb)
 	struct net *net = sock_net(skb->sk);
 	int msglen;
 
-	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
-		return netlink_ack(skb, nlh, -EPERM);
-
 	if (nlh->nlmsg_len < NLMSG_HDRLEN ||
 	    skb->len < nlh->nlmsg_len)
 		return;
 
+	if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+		netlink_ack(skb, nlh, -EPERM);
+		return;
+	}
+
 	if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) {
 		struct nfgenmsg *nfgenmsg;