netdev - [PATCH 0/2] vsock/virtio: Fix data loss/disclosure due to joining of non-linear skb in RX queue

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Message-Id: <20260108-vsock-recv-coalescence-v1-0-26f97bb9a99b@rbox.co>
Date: Thu, 08 Jan 2026 10:54:53 +0100
From: Michal Luczaj <mhal@...x.co>
To: "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
 Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
 Eugenio Pérez <eperezma@...hat.com>, 
 Stefan Hajnoczi <stefanha@...hat.com>, 
 Stefano Garzarella <sgarzare@...hat.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, 
 Arseniy Krasnov <avkrasnov@...utedevices.com>
Cc: kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Michal Luczaj <mhal@...x.co>
Subject: [PATCH 0/2] vsock/virtio: Fix data loss/disclosure due to joining
 of non-linear skb in RX queue

Loopback transport coalesces some skbs too eagerly. Handling a zerocopy
(non-linear) skb as a linear one leads to skb data loss and kernel memory
disclosure.

Plug the loss/leak by allowing only linear skb join. Provide a test.

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
Michal Luczaj (2):
      vsock/virtio: Coalesce only linear skb
      vsock/test: Add test for a linear and non-linear skb getting coalesced

 net/vmw_vsock/virtio_transport_common.c   |  3 +-
 tools/testing/vsock/vsock_test.c          |  5 +++
 tools/testing/vsock/vsock_test_zerocopy.c | 67 +++++++++++++++++++++++++++++++
 tools/testing/vsock/vsock_test_zerocopy.h |  3 ++
 4 files changed, 77 insertions(+), 1 deletion(-)
---
base-commit: 653267321f05316f159e05b3ef562aa700632db6
change-id: 20260103-vsock-recv-coalescence-38178fafd10c

Best regards,
-- 
Michal Luczaj <mhal@...x.co>