From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 3D2D21F934 for ; Mon, 19 Oct 2020 19:35:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731297AbgJSTfu (ORCPT ); Mon, 19 Oct 2020 15:35:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731280AbgJSTfs (ORCPT ); Mon, 19 Oct 2020 15:35:48 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6CE7C0613CE for ; Mon, 19 Oct 2020 12:35:47 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id g12so987727wrp.10 for ; Mon, 19 Oct 2020 12:35:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=51qnyM0oQPKf1T95ynoz0JMbhKqPGV0a/d3fTLw2UhA=; b=i4ItQs94jve7G1blO1liADjtgvZbJUTifwU1aDkQRHdYAtMfjstYD3XvflwqocY5MF 7h31C83TCOzA3eg5a2YTkiynowqKcZFETXtVDeDIynFc5LBktzgmQtqGS0vWOTXGRq36 bWBJNepO3gW4uV/UwM//H2NMjzpVM2mXQJwYjMLJrXrv4r1rOEGaiwqeLxJW/DKMUIMj BJCQxQLfBm33E9ZLRmmbZGqYN4yrNnGSteMX1JR+qUo5IC+5T33wxm75sCXPJKtd3lNB FjCav8JeU9yIi8ZJTVLB0pQ01Efb+6J3/c/KAugVGIXwgiv0AqTjKwQBqhyoKnhBnKS5 6Y3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=51qnyM0oQPKf1T95ynoz0JMbhKqPGV0a/d3fTLw2UhA=; b=q9bdzbyAYAerla6sxFKaPlqWCy6zQN8R0tmBaIaBJAx0bI0oXN0qmo19T3NmykerJ/ EB1EDKx1x+ZpSCqEAhNBVl/4C8KUiHp5tmkLo1LFtSgbFK7WjHSBRY6LJhrreDdB33f0 bzGn2lfxt41sieXNp43XzGuKcMXY0wJ5NAPHG4Zc7eAgwH6dGA8szgMjtxBRP7jBzVa/ RhlovUrNRBaGyB3WZtU6s3nSD9L9OHZt3NnzgDn9g8ZHUTGwL5yXMxQ9Cuib7zpDZCB+ vYfwu9d4hjB7j0tRPtLzEpb8csCVBAYldJWWthV5JIABd0PfhTifBOYgSaeIiuPGZGan q8gA== X-Gm-Message-State: AOAM530pNYM3TQ1ZrFcgTFneX5kUDq3i//WU/iXZ3Y912rcWMfSPuwOC C0lboEYhcIHRgHzS7Sxt8HUbO2h5hAk= X-Google-Smtp-Source: ABdhPJykYjpK4ou9paMBx/Tlr4ZeGJryzmoZg/unVdYtx8BQqUM348hIQTDXkZE3LZRVE/6Kxenx4Q== X-Received: by 2002:a5d:494c:: with SMTP id r12mr849444wrs.406.1603136146312; Mon, 19 Oct 2020 12:35:46 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id j7sm681160wmc.7.2020.10.19.12.35.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2020 12:35:45 -0700 (PDT) Message-Id: In-Reply-To: References: From: "Johannes Schindelin via GitGitGadget" Date: Mon, 19 Oct 2020 19:35:42 +0000 Subject: [PATCH v2 3/3] sideband: add defense against packets missing a band designator Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 To: git@vger.kernel.org Cc: Jonathan Tan , Jeff King , Johannes Schindelin , Johannes Schindelin , Johannes Schindelin Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Johannes Schindelin While there is currently no instance of code producing this type of packet, if the `demultiplex_sideband()` would receive a packet whose payload is not only empty but even misses the band designator, it would mistake it for a flush packet. Let's defend against such a bug in the future. Note: `demultiplex_sideband()` will treat empty flush, delim, eof and response-end packets all alike: it will treat them as flush packets. Since empty packets by definition are missing a band designator, this is the best that function can do. Therefore, it would make little sense to pass the `status` on to `demultiplex_sideband()`. Besides, fbd76cd450 (sideband: reverse its dependency on pkt-line, 2019-01-16) went out of its way to _stop_ the code inside `demultiplex_sideband()` from relying on anything in `pkt-line.h`; that includes the data type `enum packet_read_status` that we would need if we were to pass `status` as a parameter to that function. Based on a suggestion by Jeff King. Signed-off-by: Johannes Schindelin --- pkt-line.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/pkt-line.c b/pkt-line.c index 657a702927..f72048f623 100644 --- a/pkt-line.c +++ b/pkt-line.c @@ -461,8 +461,10 @@ int recv_sideband(const char *me, int in_stream, int out) enum sideband_type sideband_type; while (1) { - len = packet_read(in_stream, NULL, NULL, buf, LARGE_PACKET_MAX, - 0); + int status = packet_read_with_status(in_stream, NULL, NULL, buf, + LARGE_PACKET_MAX, &len, 0); + if (!len && status == PACKET_READ_NORMAL) + BUG("missing band designator"); if (!demultiplex_sideband(me, buf, len, 0, &scratch, &sideband_type)) continue; @@ -520,6 +522,8 @@ enum packet_read_status packet_reader_read(struct packet_reader *reader) reader->options); if (!reader->use_sideband) break; + if (!reader->pktlen && reader->status == PACKET_READ_NORMAL) + BUG("missing band designator"); if (demultiplex_sideband(reader->me, reader->buffer, reader->pktlen, 1, &scratch, &sideband_type)) -- gitgitgadget