Re: [PATCH] net/vmw_vsock: fix NULL pointer deref and improve locking
From: Eric Dumazet <hidden>
Date: 2021-02-04 21:38:29
On 2/4/21 10:28 PM, Norbert Slusarek wrote:
From: Norbert Slusarek <redacted> Date: Thu, 4 Feb 2021 18:49:24 +0100 Subject: [PATCH] net/vmw_vsock: fix NULL pointer deref and improve locking In vsock_stream_connect(), a thread will enter schedule_timeout(). While being scheduled out, another thread can enter vsock_stream_connect() as well and set vsk->transport to NULL. In case a signal was sent, the first thread can leave schedule_timeout() and vsock_transport_cancel_pkt() will be called right after. Inside vsock_transport_cancel_pkt(), a null dereference will happen on transport->cancel_pkt. The patch also features improved locking inside vsock_connect_timeout().
We request Fixes: tag for patches targeting net tree. You could also mention the vsock_connect_timeout() issue was found by a reviewer and give some credits ;)
quoted hunk ↗ jump to hunk
Signed-off-by: Norbert Slusarek <redacted> --- net/vmw_vsock/af_vsock.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 3b480ed0953a..ea7b9d208724 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c@@ -1233,7 +1233,7 @@ static int vsock_transport_cancel_pkt(struct vsock_sock *vsk) { const struct vsock_transport *transport = vsk->transport; - if (!transport->cancel_pkt) + if (!transport || !transport->cancel_pkt) return -EOPNOTSUPP; return transport->cancel_pkt(vsk);@@ -1243,7 +1243,6 @@ static void vsock_connect_timeout(struct work_struct *work) { struct sock *sk; struct vsock_sock *vsk; - int cancel = 0; vsk = container_of(work, struct vsock_sock, connect_work.work); sk = sk_vsock(vsk);@@ -1254,11 +1253,9 @@ static void vsock_connect_timeout(struct work_struct *work) 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); } --2.30.0