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([2a01:4f9:6a:4e9f::2]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5990da790efsm2591419e87.102.2025.12.17.10.12.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 10:12:28 -0800 (PST) From: Melbin K Mathew To: stefanha@redhat.com, sgarzare@redhat.com Cc: kvm@vger.kernel.org, netdev@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, Melbin K Mathew Subject: [PATCH net v4 0/4] vsock/virtio: fix TX credit handling Date: Wed, 17 Dec 2025 19:12:02 +0100 Message-Id: <20251217181206.3681159-1-mlbnkm1@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series fixes TX credit handling in virtio-vsock: Patch 1: Fix potential underflow in get_credit() using s64 arithmetic Patch 2: Cap TX credit to local buffer size (security hardening) Patch 3: Fix vsock_test seqpacket bounds test Patch 4: Add stream TX credit bounds regression test The core issue is that a malicious guest can advertise a huge buffer size via SO_VM_SOCKETS_BUFFER_SIZE, causing the host to allocate excessive sk_buff memory when sending data to that guest. On an unpatched Ubuntu 22.04 host (~64 GiB RAM), running a PoC with 32 guest vsock connections advertising 2 GiB each and reading slowly drove Slab/SUnreclaim from ~0.5 GiB to ~57 GiB; the system only recovered after killing the QEMU process. With this series applied, the same PoC shows only ~35 MiB increase in Slab/SUnreclaim, no host OOM, and the guest remains responsive. -- 2.34.1