From patchwork Sun Sep 25 20:45:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mauro Matteo Cascella X-Patchwork-Id: 12988122 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 18374C04A95 for ; Sun, 25 Sep 2022 20:48:42 +0000 (UTC) Received: from localhost ([::1]:44376 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ocYYL-0001MF-S6 for qemu-devel@archiver.kernel.org; Sun, 25 Sep 2022 16:48:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43016) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ocYVL-0000MU-Aw for qemu-devel@nongnu.org; Sun, 25 Sep 2022 16:45:35 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:31672) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ocYVG-0000gf-P6 for qemu-devel@nongnu.org; Sun, 25 Sep 2022 16:45:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1664138728; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=G85a1UWkiVHMpqTYuu2+R25oSBYe4UWW84jebp9crDg=; b=DF+YUzDpwvWohuSXA0J7bWPYHHvpikYDHDIBBP2jNVsDB4wt5A4cSrwsiqFpZ0sXn5Yn5v BCtEb3G4kgi4wYXajl7tm840sEyTXCsiVjQThX4ttaBiyEKEq1zt7/sUmEZg6FAcJPkfib IrOm87YtWT0SUPkaMwO38An0ckiFLv0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-158-i9aEtF1yN72_YCnosbxozA-1; Sun, 25 Sep 2022 16:45:24 -0400 X-MC-Unique: i9aEtF1yN72_YCnosbxozA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4FF55101A528; Sun, 25 Sep 2022 20:45:24 +0000 (UTC) Received: from f36-work.redhat.com (unknown [10.39.192.52]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7F9CE40C6EC2; Sun, 25 Sep 2022 20:45:21 +0000 (UTC) From: Mauro Matteo Cascella To: qemu-devel@nongnu.org Cc: mcascell@redhat.com, kraxel@redhat.com, tangpeng@qianxin.com Subject: [PATCH] ui/vnc-clipboard: fix integer underflow in vnc_client_cut_text_ext Date: Sun, 25 Sep 2022 22:45:11 +0200 Message-Id: <20220925204511.1103214-1-mcascell@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=mcascell@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=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: 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" Extended ClientCutText messages start with a 4-byte header. If len < 4, an integer underflow occurs in vnc_client_cut_text_ext. The result is used to decompress data in a while loop in inflate_buffer, leading to CPU consumption and denial of service. Prevent this by checking dlen in protocol_client_msg. Fixes: CVE-2022-3165 Fixes: 0bf41cab93e5 ("ui/vnc: clipboard support") Reported-by: TangPeng Signed-off-by: Mauro Matteo Cascella --- Extended Clipboard Pseudo-Encoding: https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#extended-clipboard-pseudo-encoding ui/vnc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/ui/vnc.c b/ui/vnc.c index 6a05d06147..acb3629cd8 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -2442,8 +2442,8 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len) if (len == 1) { return 8; } + uint32_t dlen = abs(read_s32(data, 4)); if (len == 8) { - uint32_t dlen = abs(read_s32(data, 4)); if (dlen > (1 << 20)) { error_report("vnc: client_cut_text msg payload has %u bytes" " which exceeds our limit of 1MB.", dlen); @@ -2456,8 +2456,13 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len) } if (read_s32(data, 4) < 0) { - vnc_client_cut_text_ext(vs, abs(read_s32(data, 4)), - read_u32(data, 8), data + 12); + if (dlen < 4) { + error_report("vnc: malformed payload (header less than 4 bytes)" + " in extended clipboard pseudo-encoding."); + vnc_client_error(vs); + break; + } + vnc_client_cut_text_ext(vs, dlen, read_u32(data, 8), data + 12); break; } vnc_client_cut_text(vs, read_u32(data, 4), data + 8);