From mboxrd@z Thu Jan 1 00:00:00 1970 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 2F7A4C433FE for ; Tue, 18 Oct 2022 16:54:31 +0000 (UTC) Received: from localhost ([::1]:44786 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1okprG-0008Vh-SP for qemu-devel@archiver.kernel.org; Tue, 18 Oct 2022 12:54:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59984) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1okpav-0005QU-J4 for qemu-devel@nongnu.org; Tue, 18 Oct 2022 12:37:42 -0400 Received: from mail-wr1-x436.google.com ([2a00:1450:4864:20::436]:35464) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1okpat-0002aI-UT for qemu-devel@nongnu.org; Tue, 18 Oct 2022 12:37:33 -0400 Received: by mail-wr1-x436.google.com with SMTP id u10so24549814wrq.2 for ; Tue, 18 Oct 2022 09:37:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=pqCspm8kxX9MiW3uJI6rVBeMtxtN1B3Wefz3u9EIq7U=; b=FcDKkgoFvEYSwyF0/sQTyg+y5jrFaaypCPJg5c9ROR+WMQ+K8hQhjfrlk4IZKyThuP SbEkIt0XzhptQA9X7lP2MfVNmMNT3ftHJ6MxLfg53HatUlesuFjB6q98KJuasXTEJbjG obQl924aHaM9bHaDyD61IkPDtpJVv8qcAQAm2xPvtbROqtSl7De67vDFqjRPT/NsxW7A OieawF9wcpYWXjNGjCbZdim3z7/AkY6LtmL7CVcmsog6YcXRQlo5dcI+Iyvkyhu7/ett rRNe35IVUHIw71FE/St0YvPePn6B3IZ8qttJ07McvG5l+l3JqfTd8rwI9hfGEqEYh0pO 17zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pqCspm8kxX9MiW3uJI6rVBeMtxtN1B3Wefz3u9EIq7U=; b=AJIkA1/MPAEp2t2tbvo03uD370PLtwI5Shftufe5l6zHz3FRXm+FeuadoD/YtPb0c4 XJ+siP8AV7Fc5zxAvA5FK50WBz6Q74uTeKWjon7bZ7rHKuQVuASSiu2JHnBBxzGYOL/6 fZeYX/cRrFcpIq5uCScC+SHlESJvTodVT13cfro8iek1N+80DriH+pmN9uBIg/LMDCEu TIMr+QERzIuKokBf+o2jOxoyeaSd7JZqDeI/y9SZIXQ9rqTtD8Mj17S/9d8oHX76PT6w sG4AhsOpDtM6QbTUTLdvTVr3AvkPh1KHIxZuaONLDK3ds1vZ5Ti4PLyMQ5eI8OL5csUM vUFA== X-Gm-Message-State: ACrzQf0PxiMDknSTGGMv+oWOlVBBw1F3GXHvE+VjEoGQlW6s1XXdPkMm pgJWa2xIuhGRusmf2dwDmzqSpg== X-Google-Smtp-Source: AMsMyM5aF0klomqHOH9VD8N/ULsHZNWr0rIjrYO7x6yhQphmmgZWvMKHuMP0a90tAg6GfXJZhCT2Ww== X-Received: by 2002:a5d:5249:0:b0:230:1ba4:b6cc with SMTP id k9-20020a5d5249000000b002301ba4b6ccmr2505383wrc.197.1666111049306; Tue, 18 Oct 2022 09:37:29 -0700 (PDT) Received: from [192.168.1.115] ([185.126.107.38]) by smtp.gmail.com with ESMTPSA id q1-20020a056000136100b002301c026acasm11628946wrz.85.2022.10.18.09.37.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Oct 2022 09:37:28 -0700 (PDT) Message-ID: Date: Tue, 18 Oct 2022 18:37:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH v2] nbd/client: Use smarter assert Content-Language: en-US To: Eric Blake , qemu-devel@nongnu.org Cc: "Dr . David Alan Gilbert" , Vladimir Sementsov-Ogievskiy , "open list:Network Block Dev..." References: <20221017191207.1255807-1-eblake@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= In-Reply-To: <20221017191207.1255807-1-eblake@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::436; envelope-from=philmd@linaro.org; helo=mail-wr1-x436.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, 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" On 17/10/22 21:12, Eric Blake wrote: > Assigning strlen() to a uint32_t and then asserting that it isn't too > large doesn't catch the case of an input string 4G in length. > Thankfully, the incoming strings can never be that large: if the > export name or query is reflecting a string the client got from the > server, we already guarantee that we dropped the NBD connection if the > server sent more than 32M in a single reply to our NBD_OPT_* request; > if the export name is coming from qemu, nbd_receive_negotiate() > asserted that strlen(info->name) <= NBD_MAX_STRING_SIZE; and > similarly, a query string via x->dirty_bitmap coming from the user was > bounds-checked in either qemu-nbd or by the limitations of QMP. > Still, it doesn't hurt to be more explicit in how we write our > assertions to not have to analyze whether inadvertent wraparound is > possible. > > Fixes: 93676c88 ("nbd: Don't send oversize strings", v4.2.0) > Reported-by: Dr. David Alan Gilbert > Signed-off-by: Eric Blake > --- > > v2: update subject line and commit message to reflect file being > touched; adjust a second nearby assertion with the same issue > > nbd/client.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/nbd/client.c b/nbd/client.c > index 30d5383cb1..90a6b7b38b 100644 > --- a/nbd/client.c > +++ b/nbd/client.c > @@ -658,11 +658,11 @@ static int nbd_send_meta_query(QIOChannel *ioc, uint32_t opt, > char *p; > > data_len = sizeof(export_len) + export_len + sizeof(queries); > - assert(export_len <= NBD_MAX_STRING_SIZE); > + assert(strlen(export) <= NBD_MAX_STRING_SIZE); > if (query) { > query_len = strlen(query); > data_len += sizeof(query_len) + query_len; > - assert(query_len <= NBD_MAX_STRING_SIZE); > + assert(strlen(query) <= NBD_MAX_STRING_SIZE); > } else { > assert(opt == NBD_OPT_LIST_META_CONTEXT); > } Nitpicking (pre-existing) the assertions could be moved before the assignations. Reviewed-by: Philippe Mathieu-Daudé