netdev - [PATCH net] net: Fix one possible memleak in ip_setup

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Message-Id: <1523845005-6353-1-git-send-email-gfree.wind@vip.163.com>
Date:   Mon, 16 Apr 2018 10:16:44 +0800
From:   gfree.wind@....163.com
To:     davem@...emloft.net, kuznet@....inr.ac.ru, netdev@...r.kernel.org
Cc:     Gao Feng <gfree.wind@....163.com>
Subject: [PATCH net] net: Fix one possible memleak in ip_setup_cork

From: Gao Feng <gfree.wind@....163.com>

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@....163.com>
---
 net/ipv4/ip_output.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4c11b81..83c73ba 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
 	 */
-- 
1.9.1