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Lunev" Subject: [PULL v2 06/13] io/channel-websock: handle a blocked write during the handshake Date: Fri, 4 Sep 2026 17:06:36 +0100 Message-ID: <20260904160643.353833-7-berrange@redhat.com> In-Reply-To: <20260904160643.353833-1-berrange@redhat.com> References: <20260904160643.353833-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Denis V. Lunev qio_channel_websock_handshake_send() treats every negative return from qio_channel_write() as fatal and passes err to error_get_pretty(). QIO_CHANNEL_ERR_BLOCK is negative but leaves err NULL, so a socket which cannot take the response immediately crashes QEMU before the client has authenticated. Keep the G_IO_OUT watch armed and retry instead. Fixes: 2d1d0e70cf3e ("io: add QIOChannelWebsock class") Fixes: CVE-2026-84788 Cc: qemu-stable@nongnu.org Cc: Daniel P. Berrangé Cc: Marc-André Lureau Reviewed-by: Daniel P. Berrangé Reviewed-by: Marc-André Lureau Signed-off-by: Denis V. Lunev Signed-off-by: Daniel P. Berrangé --- io/channel-websock.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/io/channel-websock.c b/io/channel-websock.c index 66c91ed2a2..8f27b1f12b 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -562,6 +562,11 @@ static gboolean qio_channel_websock_handshake_send(QIOChannel *ioc, wioc->encoutput.offset, &err); + if (ret == QIO_CHANNEL_ERR_BLOCK) { + /* Socket buffer is full, the G_IO_OUT watch stays armed */ + return TRUE; + } + if (ret < 0) { trace_qio_channel_websock_handshake_fail(ioc, error_get_pretty(err)); qio_task_set_error(task, err); -- 2.55.0