5.4-stable review patch. If anyone has any objections, please let me know.
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From: Stefano Garzarella sgarzare@redhat.com
[ Upstream commit fccd2b711d9628c7ce0111d5e4938652101ee30a ]
When a peer attempts to establish a connection, vsock_connect() contains a loop that waits for the state to be TCP_ESTABLISHED. However, the other peer can be fast enough to accept the connection and close it immediately, thus moving the state to TCP_CLOSING.
When this happens, the peer in the vsock_connect() is properly woken up, but since the state is not TCP_ESTABLISHED, it goes back to sleep until the timeout expires, returning -ETIMEDOUT.
If the socket state is TCP_CLOSING, waiting for the timeout is pointless. vsock_connect() can return immediately without errors or delay since the connection actually happened. The socket will be in a closing state, but this is not an issue, and subsequent calls will fail as expected.
We discovered this issue while developing a test that accepts and immediately closes connections to stress the transport switch between two connect() calls, where the first one was interrupted by a signal (see Closes link).
Reported-by: Luigi Leonardi leonardi@redhat.com Closes: https://lore.kernel.org/virtualization/bq6hxrolno2vmtqwcvb5bljfpb7mvwb3kohrv... Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Signed-off-by: Stefano Garzarella sgarzare@redhat.com Acked-by: Paolo Abeni pabeni@redhat.com Tested-by: Luigi Leonardi leonardi@redhat.com Reviewed-by: Luigi Leonardi leonardi@redhat.com Link: https://patch.msgid.link/20250328141528.420719-1-sgarzare@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/vmw_vsock/af_vsock.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 5d490633a7f11..7877515a6962e 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -1204,7 +1204,11 @@ static int vsock_stream_connect(struct socket *sock, struct sockaddr *addr, timeout = vsk->connect_timeout; prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
- while (sk->sk_state != TCP_ESTABLISHED && sk->sk_err == 0) { + /* If the socket is already closing or it is in an error state, there + * is no point in waiting. + */ + while (sk->sk_state != TCP_ESTABLISHED && + sk->sk_state != TCP_CLOSING && sk->sk_err == 0) { if (flags & O_NONBLOCK) { /* If we're not going to block, we schedule a timeout * function to generate a timeout on the connection