[AF_NETLINK]: Fix DoS in netlink_rcv_skb()

From: Martin Murray <murrayma@citi.umich.edu>

Sanity check nlmsg_len during netlink_rcv_skb.  An nlmsg_len == 0 can
cause infinite loop in kernel, effectively DoSing machine.  Noted by
Matin Murray.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a67f1b44c9a..bb50c8a9fca 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1422,7 +1422,7 @@ static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
         while (skb->len >= nlmsg_total_size(0)) {
                 nlh = (struct nlmsghdr *) skb->data;
 
-                if (skb->len < nlh->nlmsg_len)
+                if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
                         return 0;
 
                 total_len = min(NLMSG_ALIGN(nlh->nlmsg_len), skb->len);