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[82.53.135.12]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490b7e6c774sm73719575e9.1.2026.06.04.03.40.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Jun 2026 03:40:03 -0700 (PDT) Date: Thu, 4 Jun 2026 12:40:01 +0200 From: Stefano Garzarella To: Raf Dickson Cc: netdev@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, stefanha@redhat.com, bryan-bt.tan@broadcom.com, vishnu.dasa@broadcom.com, bcm-kernel-feedback-list@broadcom.com, stable@vger.kernel.org Subject: Re: [PATCH] vsock/vmci: fix sk_ack_backlog leak on failed handshake Message-ID: References: <20260526104356.469928-1-rafdog35@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260526104356.469928-1-rafdog35@gmail.com> On Tue, May 26, 2026 at 10:43:56AM +0000, Raf Dickson wrote: >When vmci_transport_recv_connecting_server() returns an error, >vmci_transport_recv_listen() calls vsock_remove_pending() but never >calls sk_acceptq_removed(). This leaves sk_ack_backlog incremented >permanently. > >Repeated handshake failures (malformed packets, queue pair alloc >failure, event subscribe failure) cause sk_ack_backlog to climb >toward sk_max_ack_backlog. Once it reaches the limit the listener >permanently refuses all new connections with -ECONNREFUSED, a >silent denial of service requiring a process restart to recover. > >The two existing sk_acceptq_removed() calls in af_vsock.c do not >cover this path: line 764 checks vsock_is_pending() which returns >false after vsock_remove_pending(), and line 1889 is only reached >on successful accept(). > >Fix by balancing sk_acceptq_added() with sk_acceptq_removed() on >the error path. > >Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") >Cc: stable@vger.kernel.org >Signed-off-by: Raf Dickson >--- > net/vmw_vsock/vmci_transport.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Acked-by: Stefano Garzarella