On Fri, Feb 05, 2021 at 03:32:02PM +0100, Norbert Slusarek wrote:
From: Norbert Slusarek <[email protected]> Date: Fri, 5 Feb 2021 13:14:05 +0100 Subject: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()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")
I have a doubt about the tag to use, since until we introduced transports in commit c0cfa2d8a788 ("vsock: add multi-transports support") this issue didn't cause many problems.
But it must be said that in the commit 380feae0def7 ("vsock: cancel packets when failing to connect") the vsock_transport_cancel_pkt() was called with the lock held in vsock_stream_connect() and without lock in vsock_connect_timeout(), so maybe this tag is okay.
Anyway, the patch LGTM: Reviewed-by: Stefano Garzarella <[email protected]>
Reported-by: Eric Dumazet <[email protected]> Signed-off-by: Norbert Slusarek <[email protected]> --- net/vmw_vsock/af_vsock.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 6894f21dc147..ad7dd9d93b5b 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -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
