[NETLINK]: Do precise netlink message allocations where possible

Account for the netlink message header size directly in nlmsg_new()
instead of relying on the caller calculate it correctly.

Replaces error handling of message construction functions when
constructing notifications with bug traps since a failure implies
a bug in calculating the size of the skb.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 8 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index d527c8977b1f..f61d81b3c61c 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1148,7 +1148,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
         if (len > sk->sk_sndbuf - 32)
                 goto out;
         err = -ENOBUFS;
-        skb = nlmsg_new(len, GFP_KERNEL);
+        skb = alloc_skb(len, GFP_KERNEL);
         if (skb==NULL)
                 goto out;
 
@@ -1435,14 +1435,13 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
         struct sk_buff *skb;
         struct nlmsghdr *rep;
         struct nlmsgerr *errmsg;
-        int size;
+        size_t payload = sizeof(*errmsg);
 
-        if (err == 0)
-                size = nlmsg_total_size(sizeof(*errmsg));
-        else
-                size = nlmsg_total_size(sizeof(*errmsg) + nlmsg_len(nlh));
+        /* error messages get the original request appened */
+        if (err)
+                payload += nlmsg_len(nlh);
 
-        skb = nlmsg_new(size, GFP_KERNEL);
+        skb = nlmsg_new(payload, GFP_KERNEL);
         if (!skb) {
                 struct sock *sk;
 
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 49bc2db7982b..70d60c818897 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -480,7 +480,7 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
         struct sk_buff *skb;
         int err;
 
-        skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+        skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
         if (skb == NULL)
                 return ERR_PTR(-ENOBUFS);