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Subject[PATCH 5.2 45/45] net/rds: An rds_sock is added too early to the hash table
Date
From: Ka-Cheong Poon <ka-cheong.poon@oracle.com>

[ Upstream commit c5c1a030a7dbf8dd4e1fa4405ae9a89dc1d2a8db ]

In rds_bind(), an rds_sock is added to the RDS bind hash table before
rs_transport is set. This means that the socket can be found by the
receive code path when rs_transport is NULL. And the receive code
path de-references rs_transport for congestion update check. This can
cause a panic. An rds_sock should not be added to the bind hash table
before all the needed fields are set.

Reported-by: syzbot+4b4f8163c2e246df3c4c@syzkaller.appspotmail.com
Signed-off-by: Ka-Cheong Poon <ka-cheong.poon@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/rds/bind.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/net/rds/bind.c b/net/rds/bind.c
index 0f4398e7f2a7a..05464fd7c17af 100644
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2019 Oracle and/or its affiliates. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
@@ -239,34 +239,30 @@ int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
goto out;
}

- sock_set_flag(sk, SOCK_RCU_FREE);
- ret = rds_add_bound(rs, binding_addr, &port, scope_id);
- if (ret)
- goto out;
-
- if (rs->rs_transport) { /* previously bound */
+ /* The transport can be set using SO_RDS_TRANSPORT option before the
+ * socket is bound.
+ */
+ if (rs->rs_transport) {
trans = rs->rs_transport;
if (trans->laddr_check(sock_net(sock->sk),
binding_addr, scope_id) != 0) {
ret = -ENOPROTOOPT;
- rds_remove_bound(rs);
- } else {
- ret = 0;
+ goto out;
}
- goto out;
- }
- trans = rds_trans_get_preferred(sock_net(sock->sk), binding_addr,
- scope_id);
- if (!trans) {
- ret = -EADDRNOTAVAIL;
- rds_remove_bound(rs);
- pr_info_ratelimited("RDS: %s could not find a transport for %pI6c, load rds_tcp or rds_rdma?\n",
- __func__, binding_addr);
- goto out;
+ } else {
+ trans = rds_trans_get_preferred(sock_net(sock->sk),
+ binding_addr, scope_id);
+ if (!trans) {
+ ret = -EADDRNOTAVAIL;
+ pr_info_ratelimited("RDS: %s could not find a transport for %pI6c, load rds_tcp or rds_rdma?\n",
+ __func__, binding_addr);
+ goto out;
+ }
+ rs->rs_transport = trans;
}

- rs->rs_transport = trans;
- ret = 0;
+ sock_set_flag(sk, SOCK_RCU_FREE);
+ ret = rds_add_bound(rs, binding_addr, &port, scope_id);

out:
release_sock(sk);
--
2.20.1


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