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=-11.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 5CD0DC43444 for ; Thu, 3 Jan 2019 15:14:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D2232070D for ; Thu, 3 Jan 2019 15:14:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546528440; bh=0EOsFbbfMriuPVfCu+ooNQDoeQxDIth1CN5P5ZIHr6Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=oZNY8vy2NeVa50Hkef2WZDuUqPqFxaUand90vnFv9o4wDSAeU03MerlcX1F1V1GoV cuXnsuyJrHM8Vp/qmhvYIsBmwIegt1Q9ROOa54uwTBluYoNCk42LD07kDoMYPpDB9o e7zBZZxZt9ccJOxHhpbFXwZB1hhPd/zE9FEIFJ/M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730904AbfACPN7 (ORCPT ); Thu, 3 Jan 2019 10:13:59 -0500 Received: from mx2.suse.de ([195.135.220.15]:35000 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728208AbfACPN7 (ORCPT ); Thu, 3 Jan 2019 10:13:59 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C4F8AAD47; Thu, 3 Jan 2019 15:13:57 +0000 (UTC) Date: Thu, 3 Jan 2019 16:13:57 +0100 From: Michal Hocko To: Roman Penyaev Cc: Andrew Morton , Andrey Ryabinin , Joe Perches , "Luis R. Rodriguez" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/3] mm/vmalloc: fix size check for remap_vmalloc_range_partial() Message-ID: <20190103151357.GR31793@dhcp22.suse.cz> References: <20190103145954.16942-1-rpenyaev@suse.de> <20190103145954.16942-2-rpenyaev@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190103145954.16942-2-rpenyaev@suse.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 03-01-19 15:59:52, Roman Penyaev wrote: > area->size can include adjacent guard page but get_vm_area_size() > returns actual size of the area. > > This fixes possible kernel crash when userspace tries to map area > on 1 page bigger: size check passes but the following vmalloc_to_page() > returns NULL on last guard (non-existing) page. Can this actually happen? I am not really familiar with all the callers of this API but VM_NO_GUARD is not really used wildly in the kernel. All I can see is kasan na arm64 which doesn't really seem to use it for vmalloc. So is the problem real or this is a mere cleanup? > Signed-off-by: Roman Penyaev > Cc: Andrew Morton > Cc: Michal Hocko > Cc: Andrey Ryabinin > Cc: Joe Perches > Cc: "Luis R. Rodriguez" > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Cc: stable@vger.kernel.org > --- > mm/vmalloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 871e41c55e23..2cd24186ba84 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2248,7 +2248,7 @@ int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr, > if (!(area->flags & VM_USERMAP)) > return -EINVAL; > > - if (kaddr + size > area->addr + area->size) > + if (kaddr + size > area->addr + get_vm_area_size(area)) > return -EINVAL; > > do { > -- > 2.19.1 -- Michal Hocko SUSE Labs