In the Linux kernel, the following vulnerability has been resolved:
vsock: Ignore signal/timeout on connect() if already established
During connect(), acting on a signal/timeout by disconnecting an already
established socket leads to several issues:
-
connect() invoking vsock_transport_cancel_pkt() ->
virtio_transport_purge_skbs() may race with sendmsg() invoking
virtio_transport_get_credit(). This results in a permanently elevated
vvs->bytes_unsent. Which, in turn, confuses the SOCK_LINGER handling.
-
connect() resetting a connected socket's state may race with socket
being placed in a sockmap. A disconnected socket remaining in a sockmap
breaks sockmap's assumptions. And gives rise to WARNs.
-
connect() transitioning SS_CONNECTED -> SS_UNCONNECTED allows for a
transport change/drop after TCP_ESTABLISHED. Which poses a problem for
any simultaneous sendmsg() or connect() and may result in a
use-after-free/null-ptr-deref.
Do not disconnect socket on signal/timeout. Keep the logic for unconnected
sockets: they don't linger, can't be placed in a sockmap, are rejected by
sendmsg().
References
In the Linux kernel, the following vulnerability has been resolved:
vsock: Ignore signal/timeout on connect() if already established
During connect(), acting on a signal/timeout by disconnecting an already
established socket leads to several issues:
connect() invoking vsock_transport_cancel_pkt() ->
virtio_transport_purge_skbs() may race with sendmsg() invoking
virtio_transport_get_credit(). This results in a permanently elevated
vvs->bytes_unsent. Which, in turn, confuses the SOCK_LINGER handling.connect() resetting a connected socket's state may race with socket
being placed in a sockmap. A disconnected socket remaining in a sockmap
breaks sockmap's assumptions. And gives rise to WARNs.
connect() transitioning SS_CONNECTED -> SS_UNCONNECTED allows for a
transport change/drop after TCP_ESTABLISHED. Which poses a problem for
any simultaneous sendmsg() or connect() and may result in a
use-after-free/null-ptr-deref.
Do not disconnect socket on signal/timeout. Keep the logic for unconnected
sockets: they don't linger, can't be placed in a sockmap, are rejected by
sendmsg().
References