CVE-2025-68775
Our Analysis: General-Purpose
Our model has classified this vulnerability as relevant to General-Purpose Systems, helping your team prioritize efforts effectively.
Description
In the Linux kernel, the following vulnerability has been resolved:
net/handshake: duplicate handshake cancellations leak socket
When a handshake request is cancelled it is removed from the
handshake_net->hn_requests list, but it is still present in the
handshake_rhashtbl until it is destroyed.
If a second cancellation request arrives for the same handshake request,
then remove_pending() will return false... and assuming
HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue
processing through the out_true label, where we put another reference on
the sock and a refcount underflow occurs.
This can happen for example if a handshake times out - particularly if
the SUNRPC client sends the AUTH_TLS probe to the server but doesn't
follow it up with the ClientHello due to a problem with tlshd. When the
timeout is hit on the server, the server will send a FIN, which triggers
a cancellation request via xs_reset_transport(). When the timeout is
hit on the client, another cancellation request happens via
xs_tls_handshake_sync().
Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel
path so duplicate cancels can be detected.