On Fri, Feb 05, 2021 at 03:32:02PM +0100, Norbert Slusarek wrote:
From: Norbert Slusarek <nslusa...@gmx.net>
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 <sgarz...@redhat.com>
Reported-by: Eric Dumazet <eric.duma...@gmail.com>
Signed-off-by: Norbert Slusarek <nslusa...@gmx.net>
---
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
