CVE-2026-23069

In the Linux kernel, the following vulnerability has been resolved:

vsock/virtio: fix potential underflow in virtiotransportget_credit()

The credit calculation in virtiotransportget_credit() uses unsigned arithmetic:

ret = vvs->peerbufalloc - (vvs->txcnt - vvs->peerfwd_cnt);

If the peer shrinks its advertised buffer (peerbufalloc) while bytes are in flight, the subtraction can underflow and produce a large positive value, potentially allowing more data to be queued than the peer can handle.

Reuse virtiotransporthas_space() which already handles this case and add a comment to make it clear why we are doing that.

[Stefano: use virtiotransporthas_space() instead of duplicating the code] [Stefano: tweak the commit message]