[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>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6b9772d9587..59dc7d14060 100644
--- 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);