Subject: [PATCH 40/49] mptcp: fix memory leak in mptcp_subflow_create_socket()

From: Wei Yongjun <[email-masked]>
Date: Mon, 15 Jun 2020 09:35:22 +0800

[ Upstream commit b8ad540dd4e40566c520dff491fc06c71ae6b989 ]

socket malloced  by sock_create_kern() should be release before return
in the error handling, otherwise it cause memory leak.

unreferenced object 0xffff88810910c000 (size 1216):
  comm "00000003_test_m", pid 12238, jiffies 4295050289 (age 54.237s)
  hex dump (first 32 bytes):
    01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 2f 30 0a 81 88 ff ff  ........./0.....
  backtrace:
    [<00000000e877f89f>] sock_alloc_inode+0x18/0x1c0
    [<0000000093d1dd51>] alloc_inode+0x63/0x1d0
    [<000000005673fec6>] new_inode_pseudo+0x14/0xe0
    [<00000000b5db6be8>] sock_alloc+0x3c/0x260
    [<00000000e7e3cbb2>] __sock_create+0x89/0x620
    [<0000000023e48593>] mptcp_subflow_create_socket+0xc0/0x5e0
    [<00000000419795e4>] __mptcp_socket_create+0x1ad/0x3f0
    [<00000000b2f942e8>] mptcp_stream_connect+0x281/0x4f0
    [<00000000c80cd5cc>] __sys_connect_file+0x14d/0x190
    [<00000000dc761f11>] __sys_connect+0x128/0x160
    [<000000008b14e764>] __x64_sys_connect+0x6f/0xb0
    [<000000007b4f93bd>] do_syscall_64+0xa1/0x530
    [<00000000d3e770b6>] entry_SYSCALL_64_after_hwframe+0x49/0xb3

Fixes: 2303f994b3e1 ("mptcp: Associate MPTCP context with TCP socket")
Signed-off-by: Wei Yongjun <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/mptcp/subflow.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index e6feb05a93dc..db3e4e74e785 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1015,8 +1015,10 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
 	err = tcp_set_ulp(sf->sk, "mptcp");
 	release_sock(sf->sk);
 
-	if (err)
+	if (err) {
+		sock_release(sf);
 		return err;
+	}
 
 	/* the newly created socket really belongs to the owning MPTCP master
 	 * socket, even if for additional subflows the allocation is performed
-- 
2.26.2