mirror of
https://github.com/cloud-hypervisor/cloud-hypervisor.git
synced 2026-08-05 02:19:16 +00:00
d28d9eb34e
The function `read_local_stream_port` had no proper handling for unexpected or incomplete input. When the control socket of the VSOCK device was closed without sending the expected `CONNECT <PORT>\n` statement completely, the thread got stuck in an infinite loop as it attempted to read from a closed socket over and over again which never returned any data. This resulted in the thread responsible for `epoll` being completely blocked. New VSOCK connections could not be established and existing ones became defunct, effectively leading to a Denial of Service of the entire VSOCK device. The issue can be reproduced by opening a socket and immediately closing it. ``` socat - UNIX-CONNECT:/socket.vsock <Ctrl-C> ``` Instead of applying a quick fix by handling the `EPOLLHUP` event before reading, the function is refactored to remove the error-prone `while` loop and multiple `read`s. Notably, we now check if the number of bytes read is zero, which occurs when `event_set == EPOLLHUP | EPOLLIN`, indicating that the socket has been closed by the client. Additionally, the actual parsing code is now extracted into a dedicated function that is tested. Fixes: #6798 Signed-off-by: Maximilian Güntner <code@mguentner.de>