net: Fix one possible memleak in ip_setup_cork

It would allocate memory in this function when the cork->opt is NULL. But
the memory isn't freed if failed in the latter rt check, and return error
directly. It causes the memleak if its caller is ip_make_skb which also
doesn't free the cork->opt when meet a error.

Now move the rt check ahead to avoid the memleak.

Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4c11b810a447..83c73bab2c3d 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1109,6 +1109,10 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
         struct ip_options_rcu *opt;
         struct rtable *rt;
 
+        rt = *rtp;
+        if (unlikely(!rt))
+                return -EFAULT;
+
         /*
          * setup for corking.
          */
@@ -1124,9 +1128,7 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
                 cork->flags |= IPCORK_OPT;
                 cork->addr = ipc->addr;
         }
-        rt = *rtp;
-        if (unlikely(!rt))
-                return -EFAULT;
+
         /*
          * We steal reference to this route, caller should not release it
          */