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Lunev" Subject: [PULL v3 05/12] io/channel-websock: send an HTTP 400 when the greeting has no space Date: Mon, 7 Sep 2026 11:53:03 +0100 Message-ID: <20260907105310.497730-6-berrange@redhat.com> In-Reply-To: <20260907105310.497730-1-berrange@redhat.com> References: <20260907105310.497730-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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_extract_headers() returns 0 without queueing a response when the request line contains no space, unlike every sibling check which jumps to bad_request. encoutput stays empty, yet qio_channel_websock_handshake_read() still reports success and the caller arms a G_IO_OUT watch to flush nothing. Flushing that empty buffer is where QEMU crashes. Any client can trigger it before authentication on a VNC websocket port: printf 'stats\r\nx\r\n\r\n' | nc $host $port Fixes: 07e95cd529af ("io: fully parse & validate HTTP headers for websocket protocol handshake") Fixes: f69a8bde2935 ("io: send proper HTTP response for websocket errors") 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 | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/io/channel-websock.c b/io/channel-websock.c index 1929abf56a..66c91ed2a2 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -230,7 +230,7 @@ qio_channel_websock_extract_headers(QIOChannelWebsock *ioc, tmp = strchr(buffer, ' '); if (!tmp) { error_setg(errp, "Missing HTTP path delimiter"); - return 0; + goto bad_request; } *tmp = '\0'; -- 2.55.0