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vsock: fix the race conditions in multi-transport support

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There are multiple similar bugs implicitly introduced by the
commit c0cfa2d8a7 ("vsock: add multi-transports support") and
commit 6a2c096210 ("vsock: prevent transport modules unloading").

The bug pattern:
 [1] vsock_sock.transport pointer is copied to a local variable,
 [2] lock_sock() is called,
 [3] the local variable is used.
VSOCK multi-transport support introduced the race condition:
vsock_sock.transport value may change between [1] and [2].

Let's copy vsock_sock.transport pointer to local variables after
the lock_sock() call.

Fixes: c0cfa2d8a7 ("vsock: add multi-transports support")
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Link: https://lore.kernel.org/r/20210201084719.2257066-1-alex.popov@linux.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Alexander Popov 2021-02-01 11:47:19 +03:00 committed by Jakub Kicinski
parent 938e0fcd32
commit c518adafa3
1 changed files with 12 additions and 5 deletions
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17
net/vmw_vsock/af_vsock.c
View file

@ -1014,9 +1014,12 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
} else if (sock->type == SOCK_STREAM) {
const struct vsock_transport *transport = vsk->transport;
const struct vsock_transport *transport;
lock_sock(sk);
transport = vsk->transport;
/* Listening sockets that have connections in their accept
* queue can be read.
*/
@ -1099,10 +1102,11 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
err = 0;
sk = sock->sk;
vsk = vsock_sk(sk);
transport = vsk->transport;
lock_sock(sk);
transport = vsk->transport;
err = vsock_auto_bind(vsk);
if (err)
goto out;
@ -1561,10 +1565,11 @@ static int vsock_stream_setsockopt(struct socket *sock,
err = 0;
sk = sock->sk;
vsk = vsock_sk(sk);
transport = vsk->transport;
lock_sock(sk);
transport = vsk->transport;
switch (optname) {
case SO_VM_SOCKETS_BUFFER_SIZE:
COPY_IN(val);
@ -1697,7 +1702,6 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
sk = sock->sk;
vsk = vsock_sk(sk);
transport = vsk->transport;
total_written = 0;
err = 0;
@ -1706,6 +1710,8 @@ static int vsock_stream_sendmsg(struct socket *sock, struct msghdr *msg,
lock_sock(sk);
transport = vsk->transport;
/* Callers should not provide a destination with stream sockets. */
if (msg->msg_namelen) {
err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
@ -1840,11 +1846,12 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
sk = sock->sk;
vsk = vsock_sk(sk);
transport = vsk->transport;
err = 0;
lock_sock(sk);
transport = vsk->transport;
if (!transport || sk->sk_state != TCP_ESTABLISHED) {
/* Recvmsg is supposed to return 0 if a peer performs an
* orderly shutdown. Differentiate between that case and when a