Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: fix potential underflow in virtio_transport_get_credit()
The credit calculation in virtio_transport_get_credit() uses unsigned arithmetic:
ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
If the peer shrinks its advertised buffer (peer_buf_alloc) 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 virtio_transport_has_space() which already handles this case and add a comment to make it clear why we are doing that.
[Stefano: use virtio_transport_has_space() instead of duplicating the code] [Stefano: tweak the commit message]
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+8 more)
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: fix potential underflow in virtio_transport_get_credit()
The credit calculation in virtio_transport_get_credit() uses unsigned arithmetic:
ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
If the peer shrinks its advertised buffer (peer_buf_alloc) 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 virtio_transport_has_space() which already handles this case and add a comment to make it clear why we are doing that.
[Stefano: use virtio_transport_has_space() instead of duplicating the code] [Stefano: tweak the commit message]