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=-5.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,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 B7607C43612 for ; Fri, 4 Jan 2019 10:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D6542173B for ; Fri, 4 Jan 2019 10:28:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546597729; bh=vvziJ1q8nIFtfmAM5UuVT+CQ0vvJJQH2vg0DM3PcSY8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dVnws6zQ54ETSBeZqYqTA3Wdqtn0VGMolU6HLCbQAyMhY4FIcWxd98CTMBHTFkGyN ZZuXlSJt61lRxAnzHVeWsDl+RkrRUt196Fp+FReUKEsAsTMuIfwk/Sf4QOPTnAQkqy TIWU2HoCX2WGRJwfeYaUYzhJ0hlDU6Ij4a1GIfcE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726970AbfADK2s (ORCPT ); Fri, 4 Jan 2019 05:28:48 -0500 Received: from mx2.suse.de ([195.135.220.15]:46490 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726749AbfADK2s (ORCPT ); Fri, 4 Jan 2019 05:28:48 -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 0F280AE03; Fri, 4 Jan 2019 10:28:47 +0000 (UTC) Date: Fri, 4 Jan 2019 11:28:46 +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: <20190104102846.GN31793@dhcp22.suse.cz> References: <20190103145954.16942-1-rpenyaev@suse.de> <20190103145954.16942-2-rpenyaev@suse.de> <20190103151357.GR31793@dhcp22.suse.cz> <20190103194054.GB31793@dhcp22.suse.cz> <5502b64d6c508f5432386d2cfe999844@suse.de> <20190104093808.GJ31793@dhcp22.suse.cz> <4630dd7797fc7934f98c01ea789105a8@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4630dd7797fc7934f98c01ea789105a8@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 Fri 04-01-19 11:21:39, Roman Penyaev wrote: > On 2019-01-04 10:38, Michal Hocko wrote: > > [...] > > > > > > > > > OK, my response was more confusing than I intended. I meant to say. Is > > > > there any in kernel code that would allow the bug have had in mind? > > > > In other words can userspace trick any existing code? > > > > > > In theory any existing caller of remap_vmalloc_range() which does > > > not have an explicit size check should trigger an oops, e.g. this is > > > a good candidate: > > > > > > *** drivers/media/usb/stkwebcam/stk-webcam.c: > > > v4l_stk_mmap[789] ret = remap_vmalloc_range(vma, > > > sbuf->buffer, > > > 0); > > > > Hmm, sbuf->buffer is allocated in stk_setup_siobuf to have > > buf->v4lbuf.length. mmap callback maps this buffer to the vma size and > > that is indeed not enforced to be <= length AFAICS. So you are right! > > > > Can we have an example in the changelog please? > > You mean to resend this particular patch with the list of possible > candidates for oops in a comment message? Sure thing. I would just reply to the original patch with an updated changelog wording (to include the above example and explain how the vma setup is completely independent on the buffer allocation and ask Andrew to update the changelog of the patch that is already in the mmotm tree). Thanks! -- Michal Hocko SUSE Labs