3.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Houcheng Lin <[email protected]>

commit b51d3fa364885a2c1e1668f88776c67c95291820 upstream.

The kernel should reserve enough room in the skb so that the DONE
message can always be appended.  However, in case of e.g. new attribute
erronously not being size-accounted for, __nfulnl_send() will still
try to put next nlmsg into this full skbuf, causing the skb to be stuck
forever and blocking delivery of further messages.

Fix issue by releasing skb immediately after nlmsg_put error and
WARN() so we can track down the cause of such size mismatch.

[ [email protected]: add tailroom/len info to WARN ]

Signed-off-by: Houcheng Lin <[email protected]>
Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 net/netfilter/nfnetlink_log.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -346,26 +346,25 @@ nfulnl_alloc_skb(struct net *net, u32 pe
        return skb;
 }
 
-static int
+static void
 __nfulnl_send(struct nfulnl_instance *inst)
 {
-       int status = -1;
-
        if (inst->qlen > 1) {
                struct nlmsghdr *nlh = nlmsg_put(inst->skb, 0, 0,
                                                 NLMSG_DONE,
                                                 sizeof(struct nfgenmsg),
                                                 0);
-               if (!nlh)
+               if (WARN_ONCE(!nlh, "bad nlskb size: %u, tailroom %d\n",
+                             inst->skb->len, skb_tailroom(inst->skb))) {
+                       kfree_skb(inst->skb);
                        goto out;
+               }
        }
-       status = nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid,
-                                  MSG_DONTWAIT);
-
+       nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid,
+                         MSG_DONTWAIT);
+out:
        inst->qlen = 0;
        inst->skb = NULL;
-out:
-       return status;
 }
 
 static void


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