vhost: Fix the crash caused by accessing the released memory

The rte_vhost_driver_unregister() vhost_user_read_cb()
vhost_user_client_reconnect() can be called at the same time by 3 threads.
when memory of vsocket is freed in rte_vhost_driver_unregister(),
then vhost_user_read_cb() maybe add vsocket to reconn_list,
the invalid memory of vsocket is accessed in vhost_user_client_reconnect().
It's a bug for vhost as client.

E.g., vhostuser port is created as client.
Thread 1 calls rte_vhost_driver_unregister() to remove
the vsocket of reconn from the reconn list.
Then “vhost-events” thread calls vhost_user_read_cb() to
add the vsocket of reconn back to the reconn list.
At this time, after thread 1 releases the vsocket memory,
the socket of vhostuser reconnects successfully,
"vhost_reconn" thread will access the released memory.

The core trace is:
Program terminated with signal 11, Segmentation fault.
The fix is to perform a delete operation again after releasing the memory

Fixes: 451dc0f ("vhost: fix crash on port deletion")
Cc: stable@dpdk.org

Signed-off-by: Xinxin Zhao <15957197901@163.com>
---
 lib/vhost/socket.c | 2 ++
 1 file changed, 2 insertions(+)
  

rerunning the failing performance test in CI testing as it was a false failure.

On Tue, Jun 25, 2024 at 2:39 AM zhaoxinxin <15957197901@163.com> wrote:
>
> The rte_vhost_driver_unregister() vhost_user_read_cb()
> vhost_user_client_reconnect() can be called at the same time by 3 threads.
> when memory of vsocket is freed in rte_vhost_driver_unregister(),
> then vhost_user_read_cb() maybe add vsocket to reconn_list,
> the invalid memory of vsocket is accessed in vhost_user_client_reconnect().
> It's a bug for vhost as client.
>
> E.g., vhostuser port is created as client.
> Thread 1 calls rte_vhost_driver_unregister() to remove
> the vsocket of reconn from the reconn list.
> Then “vhost-events” thread calls vhost_user_read_cb() to
> add the vsocket of reconn back to the reconn list.
> At this time, after thread 1 releases the vsocket memory,
> the socket of vhostuser reconnects successfully,
> "vhost_reconn" thread will access the released memory.
>
> The core trace is:
> Program terminated with signal 11, Segmentation fault.
> The fix is to perform a delete operation again after releasing the memory
>
> Fixes: 451dc0f ("vhost: fix crash on port deletion")
> Cc: stable@dpdk.org
>
> Signed-off-by: Xinxin Zhao <15957197901@163.com>
> ---
>  lib/vhost/socket.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
> index a75728a2e4..01946096c4 100644
> --- a/lib/vhost/socket.c
> +++ b/lib/vhost/socket.c
> @@ -1121,6 +1121,8 @@ rte_vhost_driver_unregister(const char *path)
>                 if (vsocket->is_server) {
>                         close(vsocket->socket_fd);
>                         unlink(path);
> +               } else if (vsocket->reconnect) {
> +                       vhost_user_remove_reconnect(vsocket);
>                 }
>
>                 pthread_mutex_destroy(&vsocket->conn_mutex);
> --
> 2.45.2
>