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Commit 30f91687 authored by Xin Long's avatar Xin Long Committed by Greg Kroah-Hartman
Browse files

tipc: set con sock in tipc_conn_alloc 



[ Upstream commit 0e5d56c64afcd6fd2d132ea972605b66f8a7d3c4 ]

A crash was reported by Wei Chen:

  BUG: kernel NULL pointer dereference, address: 0000000000000018
  RIP: 0010:tipc_conn_close+0x12/0x100
  Call Trace:
   tipc_topsrv_exit_net+0x139/0x320
   ops_exit_list.isra.9+0x49/0x80
   cleanup_net+0x31a/0x540
   process_one_work+0x3fa/0x9f0
   worker_thread+0x42/0x5c0

It was caused by !con->sock in tipc_conn_close(). In tipc_topsrv_accept(),
con is allocated in conn_idr then its sock is set:

  con = tipc_conn_alloc();
  ...                    <----[1]
  con->sock = newsock;

If tipc_conn_close() is called in anytime of [1], the null-pointer-def
is triggered by con->sock->sk due to con->sock is not yet set.

This patch fixes it by moving the con->sock setting to tipc_conn_alloc()
under s->idr_lock. So that con->sock can never be NULL when getting the
con from s->conn_idr. It will be also safer to move con->server and flag
CF_CONNECTED setting under s->idr_lock, as they should all be set before
tipc_conn_alloc() is called.

Fixes: c5fa7b3c ("tipc: introduce new TIPC server infrastructure")
Reported-by: default avatarWei Chen <harperchen1110@gmail.com>
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Acked-by: default avatarJon Maloy <jmaloy@redhat.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 5c12136c

net/tipc/topsrv.c

+5 −6
Original line number Diff line number Diff line
@@ -177,7 +177,7 @@ static void tipc_conn_close(struct tipc_conn *con) 
	conn_put(con);

}



static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)

static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s, struct socket *sock)

{

	struct tipc_conn *con;

	int ret;
@@ -203,10 +203,11 @@ static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s) 
	}

	con->conid = ret;

	s->idr_in_use++;

	spin_unlock_bh(&s->idr_lock);



	set_bit(CF_CONNECTED, &con->flags);

	con->server = s;

	con->sock = sock;

	spin_unlock_bh(&s->idr_lock);



	return con;

}
@@ -467,7 +468,7 @@ static void tipc_topsrv_accept(struct work_struct *work) 
		ret = kernel_accept(lsock, &newsock, O_NONBLOCK);

		if (ret < 0)

			return;

		con = tipc_conn_alloc(srv);

		con = tipc_conn_alloc(srv, newsock);

		if (IS_ERR(con)) {

			ret = PTR_ERR(con);

			sock_release(newsock);
@@ -479,7 +480,6 @@ static void tipc_topsrv_accept(struct work_struct *work) 
		newsk->sk_data_ready = tipc_conn_data_ready;

		newsk->sk_write_space = tipc_conn_write_space;

		newsk->sk_user_data = con;

		con->sock = newsock;

		write_unlock_bh(&newsk->sk_callback_lock);



		/* Wake up receive process in case of 'SYN+' message */
@@ -577,12 +577,11 @@ bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower, 
	sub.filter = filter;

	*(u64 *)&sub.usr_handle = (u64)port;



	con = tipc_conn_alloc(tipc_topsrv(net));

	con = tipc_conn_alloc(tipc_topsrv(net), NULL);

	if (IS_ERR(con))

		return false;



	*conid = con->conid;

	con->sock = NULL;

	rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub);

	if (rc >= 0)

		return true;