From patchwork Thu Mar 10 14:19:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 550361 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0CBDC43217 for ; Thu, 10 Mar 2022 14:34:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244423AbiCJOf1 (ORCPT ); Thu, 10 Mar 2022 09:35:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245148AbiCJOeQ (ORCPT ); Thu, 10 Mar 2022 09:34:16 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15616135722; Thu, 10 Mar 2022 06:31:44 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 31EA561B23; Thu, 10 Mar 2022 14:31:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EB2DC340EB; Thu, 10 Mar 2022 14:31:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646922693; bh=WW3DOoq91ik363zaWmSo3HAXnnIJnEoktcdQieptd8g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vO/FqpAxaq0G+yIOsP1mQzwcgIJWLFFyzduB7Bh6KUHBALm/GWiv0igqH4zb3EI7c fyDhzGOfOpNnyEvY4XVOsAVqXsUnk6owQ2FWTxNWJgiuTcuhclxwvaSPCynhJ23RzB QI/CbVXB84053PjMw0GQZfDvjTTSqjnup6ITna/w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Simon Gaiser , Juergen Gross , Jan Beulich Subject: [PATCH 5.15 54/58] xen/9p: use alloc/free_pages_exact() Date: Thu, 10 Mar 2022 15:19:43 +0100 Message-Id: <20220310140814.517099150@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310140812.983088611@linuxfoundation.org> References: <20220310140812.983088611@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Juergen Gross Commit 5cadd4bb1d7fc9ab201ac14620d1a478357e4ebd upstream. Instead of __get_free_pages() and free_pages() use alloc_pages_exact() and free_pages_exact(). This is in preparation of a change of gnttab_end_foreign_access() which will prohibit use of high-order pages. By using the local variable "order" instead of ring->intf->ring_order in the error path of xen_9pfs_front_alloc_dataring() another bug is fixed, as the error path can be entered before ring->intf->ring_order is being set. By using alloc_pages_exact() the size in bytes is specified for the allocation, which fixes another bug for the case of order < (PAGE_SHIFT - XEN_PAGE_SHIFT). This is part of CVE-2022-23041 / XSA-396. Reported-by: Simon Gaiser Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Signed-off-by: Greg Kroah-Hartman --- net/9p/trans_xen.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -304,9 +304,9 @@ static void xen_9pfs_front_free(struct x ref = priv->rings[i].intf->ref[j]; gnttab_end_foreign_access(ref, 0, 0); } - free_pages((unsigned long)priv->rings[i].data.in, - priv->rings[i].intf->ring_order - - (PAGE_SHIFT - XEN_PAGE_SHIFT)); + free_pages_exact(priv->rings[i].data.in, + 1UL << (priv->rings[i].intf->ring_order + + XEN_PAGE_SHIFT)); } gnttab_end_foreign_access(priv->rings[i].ref, 0, 0); free_page((unsigned long)priv->rings[i].intf); @@ -345,8 +345,8 @@ static int xen_9pfs_front_alloc_dataring if (ret < 0) goto out; ring->ref = ret; - bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, - order - (PAGE_SHIFT - XEN_PAGE_SHIFT)); + bytes = alloc_pages_exact(1UL << (order + XEN_PAGE_SHIFT), + GFP_KERNEL | __GFP_ZERO); if (!bytes) { ret = -ENOMEM; goto out; @@ -377,9 +377,7 @@ out: if (bytes) { for (i--; i >= 0; i--) gnttab_end_foreign_access(ring->intf->ref[i], 0, 0); - free_pages((unsigned long)bytes, - ring->intf->ring_order - - (PAGE_SHIFT - XEN_PAGE_SHIFT)); + free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT)); } gnttab_end_foreign_access(ring->ref, 0, 0); free_page((unsigned long)ring->intf);