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 X-Spam-Level: X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2C2DC43457 for ; Mon, 12 Oct 2020 21:06:18 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 3465F206DC for ; Mon, 12 Oct 2020 21:06:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="o0RhylCe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3465F206DC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55164 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kS51N-0000Sr-5m for qemu-devel@archiver.kernel.org; Mon, 12 Oct 2020 17:06:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38576) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kS4Wq-0003JB-Fm for qemu-devel@nongnu.org; Mon, 12 Oct 2020 16:34:44 -0400 Received: from mail-il1-x144.google.com ([2607:f8b0:4864:20::144]:35605) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kS4Wo-0002nB-Q8 for qemu-devel@nongnu.org; Mon, 12 Oct 2020 16:34:44 -0400 Received: by mail-il1-x144.google.com with SMTP id o18so17211713ill.2 for ; Mon, 12 Oct 2020 13:34:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2OI/+eHzIyJYt8c4T3AdeNt7wPrS2BpKGHdtztzIHLw=; b=o0RhylCewc+7tpNZ0ijyjo/jWQGRgCKnMYv0KyNWInpVsTnpag/CRTR5s+CyoJ7XRC 3s7nYHksjGulFtYnsmPiesSMsMrPCJeSN/iV2mS06OVbVmVk43dNwio1khG2G8hbrLry m8if+3srdby6fz+3UBvIenaHIe2rCtgpLKQIJ/439Ao8flqRVfcWGC497Eh5jGuji+fm Y0pH62YEyXepw9grPm1hzxJTL/T3TGt85mlpaMBTi0YkBzezx/iUtgQV3+04AaDti4yo Mqck/AmOyM0p/qCBjh2KCo6xWi7SoCSOZzm0A8RWBbdkyZq7fL29mQsRv8A97vShxGqm 0ESQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2OI/+eHzIyJYt8c4T3AdeNt7wPrS2BpKGHdtztzIHLw=; b=Tn6k1GBe/RX84yv1gyonePJb/6xKuzmQkHTmK+htdzcOa1wBJGHpQGdC/lboe63m3N CuH0kYXjWyUAEemfNponaO4KebrnX7+3WT4NvBV6cu8wjyBPNScPWCr3e2meyMzG7WDc UvrTt5NG5SP874g7pcS9MAw7ZYHUlRTACn5rb/q6GsSJzymxuYsX1LykmwUJ3IehQjnc /OszuzbUwTtQFgXGiOV8it0XuVRfmg7g1/gSlY+4FGnb5GWO0eHi83T1Bwtr8kE+WWcP k7CQeRzTJ54NmkVL5pWbsWo0SdB/4XoFPoOiKxbVp8wmIBxuBADcGuY5m2Wm+nJ1wUH/ bOZQ== X-Gm-Message-State: AOAM533HtxAR1xwJ7x17hn2gvluS1QMlORnLtSeBCghjAfpPyPc7RaZ8 PWKWi2o2NPTJYNNHQqbyMD01SJOoFAmHodSmcFY= X-Google-Smtp-Source: ABdhPJy4542/Q67ht2+UEwtSJfpnnJ5TUaSNA9B8i9sz+JzFnf2NOs/ub+RszBhCZ3cY2jMt4d0Uvnt9K0uFBg8YjGc= X-Received: by 2002:a92:907:: with SMTP id y7mr471808ilg.276.1602534881269; Mon, 12 Oct 2020 13:34:41 -0700 (PDT) MIME-Version: 1.0 References: <20201012150356.79670-1-mcascell@redhat.com> In-Reply-To: <20201012150356.79670-1-mcascell@redhat.com> From: Paul Zimmerman Date: Mon, 12 Oct 2020 13:34:14 -0700 Message-ID: Subject: Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet() To: Mauro Matteo Cascella Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::144; envelope-from=pauldzim@gmail.com; helo=mail-il1-x144.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. 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, FREEMAIL_FROM=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gaoning.pgn@antgroup.com, linyi.lxw@antfin.com, QEMU Developers , Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Oct 12, 2020 at 8:05 AM Mauro Matteo Cascella wrote: > > Check the value of mps before it is used as divisor. Since HCCHAR_MPS is guest > controllable, this prevents a malicious/buggy guest from crashing the QEMU > process on the host. > > Signed-off-by: Mauro Matteo Cascella > Reported-by: Gaoning Pan > Reported-by: Xingwei Lin > --- > hw/usb/hcd-dwc2.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/hw/usb/hcd-dwc2.c b/hw/usb/hcd-dwc2.c > index 97688d21bf..91476fd781 100644 > --- a/hw/usb/hcd-dwc2.c > +++ b/hw/usb/hcd-dwc2.c > @@ -324,6 +324,12 @@ babble: > } > } > > + if (mps == 0) { > + qemu_log_mask(LOG_GUEST_ERROR, > + "%s: Bad HCCHAR_MPS set to zero\n", __func__); > + return; > + } > + > tpcnt = actual / mps; > if (actual % mps) { > tpcnt++; > -- > 2.26.2 > Hi Mauro, I think it would be better to move this check earlier in the function, just after 'mps' is read from the register. Otherwise it can get assigned to 'tlen' and 'p->mps', and who knows what mischief an invalid value there might cause. After that, you can add my Reviewed-by: Paul Zimmerman Thanks, Paul