From patchwork Fri Nov 19 20:29:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Stabellini X-Patchwork-Id: 12629533 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) (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 1CCA4C433EF for ; Fri, 19 Nov 2021 20:30:39 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 C97E961108 for ; Fri, 19 Nov 2021 20:30:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C97E961108 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.228260.394926 (Exim 4.92) (envelope-from ) id 1moAWN-0004Gb-PR; Fri, 19 Nov 2021 20:30:07 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 228260.394926; Fri, 19 Nov 2021 20:30:07 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1moAWN-0004GU-Lt; Fri, 19 Nov 2021 20:30:07 +0000 Received: by outflank-mailman (input) for mailman id 228260; Fri, 19 Nov 2021 20:30:05 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1moAWL-00044k-LK for xen-devel@lists.xenproject.org; Fri, 19 Nov 2021 20:30:05 +0000 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 76098ce3-4977-11ec-a9d2-d9f7a1cc8784; Fri, 19 Nov 2021 21:29:59 +0100 (CET) Received: by mail.kernel.org (Postfix) with ESMTPSA id 5D08761108; Fri, 19 Nov 2021 20:29:56 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 76098ce3-4977-11ec-a9d2-d9f7a1cc8784 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637353796; bh=ToeTFTsoG8RQjmG78bJhuXqP6zSZHWT6qNk31D0MUoU=; h=From:To:Cc:Subject:Date:From; b=HY0Wc0K3QU2jjN81tsHd7ofj+cn8CV/0zrvORkAufQty7mgSC5HNLx5jH2utPuyqK h1AgZo9MEqDHOPlWQ4Fk0NHudI/ZO67jSVP+0ZeIFY+fvBCdSYLjWyRy/3B4J9/DkO XEldKjW38qyT8TNQiscbakt71vNHJxNaH4jXrGOtkyPEmStyMR0rWKSAUgLM4QwtyN LdaKPCNa4n2T77M0QvxBUu9/5/gk0tS2+tvGwNEQKWIQ7Y2XWFX59lkdTzkO2qJ8vL YbZzsrmxYctOuMNtFhv7qmdcxG/UIR7+AwJQMTL+7ixA1Lb1hDlG+lhL309Lm5rjfA ak/Iv7GH6QuSw== From: Stefano Stabellini To: jgross@suse.com Cc: boris.ostrovsky@oracle.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, sstabellini@kernel.org, jbeulich@suse.com, Stefano Stabellini , stable@vger.kernel.org Subject: [PATCH v2] xen: detect uninitialized xenbus in xenbus_init Date: Fri, 19 Nov 2021 12:29:51 -0800 Message-Id: <20211119202951.403525-1-sstabellini@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 From: Stefano Stabellini If the xenstore page hasn't been allocated properly, reading the value of the related hvm_param (HVM_PARAM_STORE_PFN) won't actually return error. Instead, it will succeed and return zero. Instead of attempting to xen_remap a bad guest physical address, detect this condition and return early. Note that although a guest physical address of zero for HVM_PARAM_STORE_PFN is theoretically possible, it is not a good choice and zero has never been validly used in that capacity. Also recognize the invalid value of INVALID_PFN which is ULLONG_MAX. For 32-bit Linux, any pfn above ULONG_MAX would get truncated. Pfns above ULONG_MAX should never be passed by the Xen tools to HVM guests anyway, so check for this condition and return early. Cc: stable@vger.kernel.org Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky --- Changes in v2: - add check for ULLONG_MAX (unitialized) - add check for ULONG_MAX #if BITS_PER_LONG == 32 (actual error) - add pr_err error message drivers/xen/xenbus/xenbus_probe.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 94405bb3829e..c7472ff27a93 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -951,6 +951,20 @@ static int __init xenbus_init(void) err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v); if (err) goto out_error; + /* Uninitialized. */ + if (v == 0 || v == ULLONG_MAX) { + err = -ENOENT; + goto out_error; + } + /* Avoid truncation on 32-bit. */ +#if BITS_PER_LONG == 32 + if (v > ULONG_MAX) { + pr_err("%s: cannot handle HVM_PARAM_STORE_PFN=%llx > ULONG_MAX\n", + __func__, v); + err = -EINVAL; + goto out_error; + } +#endif xen_store_gfn = (unsigned long)v; xen_store_interface = xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,