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bh=DvwmNHCQyt34NpybuLwlaeryZi7wm7zvb0vdyD5HB74=; b=FoARwMRqZY27B5qFdZSqL38I7ch9bdQ8qRq0IUhyiIDLRZ3DuTl5Z5ZRXqmwZIS+0Ldv0N 0O+kcz2ADTN62fDVriwp4lNdGjHyoeEyu6QdQH41PwfKGUg1ticZz80+cd6oC5uDSM7DhX 0StjSyPrKH+OtZwBOvO2lDw9i5vC2tc= X-MC-Unique: uIPGQWqGMHCiuI-ekJBkJw-1 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Fiona Ebner , Markus Frank , Gerd Hoffmann , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH] ui: reject extended clipboard message if not activated Date: Mon, 15 Jan 2024 09:51:19 +0000 Message-ID: <20240115095119.654271-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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: -48 X-Spam_score: -4.9 X-Spam_bar: ---- X-Spam_report: (-4.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.758, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1705312308753100003 The extended clipboard message protocol requires that the client activate the extension by requesting a psuedo encoding. If this is not done, then any extended clipboard messages from the client should be considered invalid and the client dropped. Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Marc-Andr=C3=A9 Lureau --- The need for fix was identified as part of investigation for CVE-2023-6683. This does NOT, however, fix that CVE as it only addresses one of the problem codepaths that can trigger that CVE. ui/vnc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/ui/vnc.c b/ui/vnc.c index 4f23a0fa79..3b2c71e653 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -2445,6 +2445,11 @@ static int protocol_client_msg(VncState *vs, uint8_t= *data, size_t len) } =20 if (read_s32(data, 4) < 0) { + if (!vnc_has_feature(vs, VNC_FEATURE_CLIPBOARD_EXT)) { + error_report("vnc: extended clipboard message while disabl= ed"); + vnc_client_error(vs); + break; + } if (dlen < 4) { error_report("vnc: malformed payload (header less than 4 b= ytes)" " in extended clipboard pseudo-encoding."); --=20 2.43.0