On Fri, Mar 28, 2025 at 03:15:28PM +0100, Stefano Garzarella wrote:
From: Stefano Garzarella <sgarz...@redhat.com>
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 <leona...@redhat.com>
Closes:
https://lore.kernel.org/virtualization/bq6hxrolno2vmtqwcvb5bljfpb7mvwb3kohrvaed6auz5vxrfv@ijmd2f3grobn/
Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
---
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 7e3db87ae433..fc6afbc8d680 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1551,7 +1551,11 @@ static int vsock_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
--
2.49.0
Just tested and fixes the issue! Thanks Stefano!
Tested-by: Luigi Leonardi <leona...@redhat.com>
Reviewed-by: Luigi Leonardi <leona...@redhat.com>
