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| author | Stefano Garzarella <sgarzare@redhat.com> | 2025-03-28 15:15:28 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-04-02 17:19:30 -0700 |
| commit | fccd2b711d9628c7ce0111d5e4938652101ee30a (patch) | |
| tree | 2f7912381ff7761bfcc9a8bba4fb1d028d72818a | |
| parent | 0ff0faf7afb4f990dceb0d9f8041fa00e118bc0d (diff) | |
| download | linux-fccd2b711d9628c7ce0111d5e4938652101ee30a.tar.gz linux-fccd2b711d9628c7ce0111d5e4938652101ee30a.tar.bz2 linux-fccd2b711d9628c7ce0111d5e4938652101ee30a.zip | |
vsock: avoid timeout during connect() if the socket is closing
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/bq6hxrolno2vmtqwcvb5bljfpb7mvwb3kohrvaed6auz5vxrfv@ijmd2f3grobn/
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>
| -rw-r--r-- | net/vmw_vsock/af_vsock.c | 6 |
1 files changed, 5 insertions, 1 deletions
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 |