[NETLINK]: Fix use-after-free in netlink_recvmsg

The skb given to netlink_cmsg_recv_pktinfo is already freed, move it up
a few lines.

Coverity #948

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6b9772d95872245b71cd305eda34f57335ac406c..59dc7d140600d95ec10a495beaed0f37f4f390e5 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1194,6 +1194,9 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
                msg->msg_namelen = sizeof(*addr);
        }
 
+       if (nlk->flags & NETLINK_RECV_PKTINFO)
+               netlink_cmsg_recv_pktinfo(msg, skb);
+
        if (NULL == siocb->scm) {
                memset(&scm, 0, sizeof(scm));
                siocb->scm = &scm;
@@ -1205,8 +1208,6 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
                netlink_dump(sk);
 
        scm_recv(sock, msg, siocb->scm, flags);
-       if (nlk->flags & NETLINK_RECV_PKTINFO)
-               netlink_cmsg_recv_pktinfo(msg, skb);
 
 out:
        netlink_rcv_wake(sk);