From patchwork Wed Oct 16 10:53:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11193077 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 A4D6F17E6 for ; Wed, 16 Oct 2019 10:54:26 +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 865602067D for ; Wed, 16 Oct 2019 10:54:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 865602067D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iKgvX-0002lf-9G; Wed, 16 Oct 2019 10:53:11 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iKgvW-0002lW-2J for xen-devel@lists.xenproject.org; Wed, 16 Oct 2019 10:53:10 +0000 X-Inumbo-ID: 241df2a6-f003-11e9-8aca-bc764e2007e4 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-iad1.inumbo.com (Halon) with ESMTP id 241df2a6-f003-11e9-8aca-bc764e2007e4; Wed, 16 Oct 2019 10:53:09 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 04BEA28; Wed, 16 Oct 2019 03:53:09 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 259B63F6C4; Wed, 16 Oct 2019 03:53:07 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Wed, 16 Oct 2019 11:53:03 +0100 Message-Id: <20191016105303.21948-1-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 Subject: [Xen-devel] [PATCH for-4.13 v2] xen/arm: Don't use _end in is_xen_fixed_mfn() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Julien Grall , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Tim Deegan , Julien Grall , Jan Beulich , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" virt_to_maddr() is using the hardware page-table walk instructions to translate a virtual address to physical address. The function should only be called on virtual address mapped. _end points past the end of Xen binary and may not be mapped when the binary size is page-aligned. This means virt_to_maddr() will not be able to do the translation and therefore crash Xen. Note there is also an off-by-one issue in this code, but the panic will trump that. Both issues can be fixed by using _end - 1 in the check. Signed-off-by: Julien Grall Release-acked-by: Juergen Gross Reviewed-by: Stefano Stabellini --- Cc: Andrew Cooper Cc: George Dunlap Cc: Ian Jackson Cc: Jan Beulich Cc: Julien Grall Cc: Konrad Rzeszutek Wilk Cc: Stefano Stabellini Cc: Tim Deegan Cc: Wei Liu x86 seems to be affected by the off-by-one issue. Jan, Andrew? This could be reached by a domain via XEN_SYSCTL_page_offline_op. However, the operation is not security supported (see XSA-77). So we are fine here. Changes in v2: - Cast _end to vaddr_t to prevent UB. - Add Juergen's released-acked-by --- xen/include/asm-arm/mm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h index 262d92f18d..333efd3a60 100644 --- a/xen/include/asm-arm/mm.h +++ b/xen/include/asm-arm/mm.h @@ -153,7 +153,7 @@ extern unsigned long xenheap_base_pdx; #define is_xen_fixed_mfn(mfn) \ ((mfn_to_maddr(mfn) >= virt_to_maddr(&_start)) && \ - (mfn_to_maddr(mfn) <= virt_to_maddr(&_end))) + (mfn_to_maddr(mfn) <= virt_to_maddr((vaddr_t)_end - 1))) #define page_get_owner(_p) (_p)->v.inuse.domain #define page_set_owner(_p,_d) ((_p)->v.inuse.domain = (_d))