[PATCH 4.14 35/57] net/vmw_vsock: improve locking in vsock_connect_timeout()

Greg Kroah-Hartman
2021-02-22T13:25:49Z

From: Norbert Slusarek <nslusarek@gmx.net>

commit 3d0bc44d39bca615b72637e340317b7899b7f911 upstream.

A possible locking issue in vsock_connect_timeout() was recognized by
Eric Dumazet which might cause a null pointer dereference in
vsock_transport_cancel_pkt(). This patch assures that
vsock_transport_cancel_pkt() will be called within the lock, so a race
condition won't occur which could result in vsk->transport to be set to NULL.

Fixes: 380feae0def7 ("vsock: cancel packets when failing to connect")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/trinity-f8e0937a-cf0e-4d80-a76e-d9a958ba3ef1-1612535522360@3c-app-gmx-bap12
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/vmw_vsock/af_vsock.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1114,7 +1114,6 @@ static void vsock_connect_timeout(struct
{
struct sock *sk;
struct vsock_sock *vsk;
- int cancel = 0;

vsk = container_of(work, struct vsock_sock, connect_work.work);
sk = sk_vsock(vsk);
@@ -1125,11 +1124,9 @@ static void vsock_connect_timeout(struct
sk->sk_state = TCP_CLOSE;
sk->sk_err = ETIMEDOUT;
sk->sk_error_report(sk);
- cancel = 1;
+ vsock_transport_cancel_pkt(vsk);
}
release_sock(sk);
- if (cancel)
- vsock_transport_cancel_pkt(vsk);

sock_put(sk);
}