From patchwork Fri Jun 19 21:53:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 11615137 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D103014E3 for ; Fri, 19 Jun 2020 21:54:20 +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 A76BE221F8 for ; Fri, 19 Jun 2020 21:54:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IJyG9T3l" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A76BE221F8 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:47956 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jmOxn-0000ie-Sx for patchwork-qemu-devel@patchwork.kernel.org; Fri, 19 Jun 2020 17:54:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40028) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jmOwk-00075o-V8 for qemu-devel@nongnu.org; Fri, 19 Jun 2020 17:53:14 -0400 Received: from mail-pg1-x542.google.com ([2607:f8b0:4864:20::542]:39337) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jmOwj-00029o-Bd for qemu-devel@nongnu.org; Fri, 19 Jun 2020 17:53:14 -0400 Received: by mail-pg1-x542.google.com with SMTP id v11so5056770pgb.6 for ; Fri, 19 Jun 2020 14:53:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:date:message-id:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=fLhsBOE/Ie7X1lQJNtWOQpBAge+hkeMZxYyQv8gw5/8=; b=IJyG9T3lTnQz4uBf4iAzffv+bWmkF2o8P8OIgsxWK9fPFQHFkzedwWw2Eau/434Sqy z4Al1ez+CHki30TFREbs1pnSCBwx/Qfhs5QZhOQoebBrznB/WnXVcbs4dQ2vMMw4LLiv rkMQuSPtoouqk0CSCfzyRmHP3EXy3FdgBp57vUkd5M8wXj6y/5jcGspWzD7zuTmeMHfW RnaOseO7nVYHMna38Pf1v50aGRG/cWFbxnVin1F/93PrO8FMLzF9mpgA5KFsbY4TDqYp 35rekHevZX+UaM4qrtvNYTlp/aEnDsGyZuH5B+RufMLRi7StpVdCwFyUg8ujSLHrIA0b T5HQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=fLhsBOE/Ie7X1lQJNtWOQpBAge+hkeMZxYyQv8gw5/8=; b=S2us26Wrv7ZEu/qCIsUK2uZUvsRtZS/QjM0/YelJHTGDxhAttNJA0hsGxa1Qq71EML +HWszHIQ0apoakt97MDuARilYVK1cyCEjqQq+iM5Lm6lHPLOnBfpqHxMDyNmlJIVEb0y sYN4v7yoH1TWSiIXRx0dRs1Q4l1o2rwFBorCu2laWsSiOTqev3nzlErWKzaYgetvCExl WtilGFQsfIXV3HKLsITurVZf2Itq0nlFhDC3GoWQUyUElSLiBFjiRO3GmvGq5vjMkIqq Xyyp3Jbg1+/FHuczixQHQj/iIjGQTfMakxP7fAbfkhWEc9MPlHYMzjrSjs4MneqgkNV1 kAPQ== X-Gm-Message-State: AOAM533FM14ijI94ZIXQvdvNi36HvgHgLAnjlrsr7pIq1JyxfXl7uQfY 8j1YCsapf5+cmXjvXJ1JL88= X-Google-Smtp-Source: ABdhPJxbpA2QKrEQyIRN6qxwBvqW/4nmdjrcJVH9WC8KYYNn6S0qkate1ur94/Qu/db0SV+wy2vziA== X-Received: by 2002:a65:4488:: with SMTP id l8mr4564203pgq.327.1592603590871; Fri, 19 Jun 2020 14:53:10 -0700 (PDT) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id t24sm5850531pgm.10.2020.06.19.14.53.10 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jun 2020 14:53:10 -0700 (PDT) Subject: [PATCH 1/2] virtio-balloon: Prevent guest from starting a report when we didn't request one From: Alexander Duyck To: david@redhat.com, mst@redhat.com Date: Fri, 19 Jun 2020 14:53:09 -0700 Message-ID: <20200619215309.25598.7553.stgit@localhost.localdomain> In-Reply-To: <20200619214912.25598.8400.stgit@localhost.localdomain> References: <20200619214912.25598.8400.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::542; envelope-from=alexander.duyck@gmail.com; helo=mail-pg1-x542.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=_AUTOLEARN 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: virtio-dev@lists.oasis-open.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Alexander Duyck Based on code review it appears possible for the driver to force the device out of a stopped state when hinting by repeating the last ID it was provided. Prevent this by only allowing a transition to the start state when we are in the requested state. This way the driver is only allowed to send one descriptor that will transition the device into the start state. All others will leave it in the stop state once it has finished. In addition add the necessary locking to provent any potential races between the accesses of the cmd_id and the status. Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Signed-off-by: Alexander Duyck Acked-by: David Hildenbrand --- hw/virtio/virtio-balloon.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 10507b2a430a..7f3af266f674 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -527,7 +527,8 @@ static bool get_free_page_hints(VirtIOBalloon *dev) ret = false; goto out; } - if (id == dev->free_page_report_cmd_id) { + if (dev->free_page_report_status == FREE_PAGE_REPORT_S_REQUESTED && + id == dev->free_page_report_cmd_id) { dev->free_page_report_status = FREE_PAGE_REPORT_S_START; } else { /* @@ -592,14 +593,16 @@ static void virtio_balloon_free_page_start(VirtIOBalloon *s) return; } - if (s->free_page_report_cmd_id == UINT_MAX) { + qemu_mutex_lock(&s->free_page_lock); + + if (s->free_page_report_cmd_id++ == UINT_MAX) { s->free_page_report_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; - } else { - s->free_page_report_cmd_id++; } s->free_page_report_status = FREE_PAGE_REPORT_S_REQUESTED; + qemu_mutex_unlock(&s->free_page_lock); + virtio_notify_config(vdev); }