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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 3CCBAC43612 for ; Fri, 4 Jan 2019 10:21:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0894720874 for ; Fri, 4 Jan 2019 10:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726497AbfADKVm (ORCPT ); Fri, 4 Jan 2019 05:21:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:45404 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725958AbfADKVl (ORCPT ); Fri, 4 Jan 2019 05:21:41 -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 474E7AD7E; Fri, 4 Jan 2019 10:21:40 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 04 Jan 2019 11:21:39 +0100 From: Roman Penyaev To: Michal Hocko 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() In-Reply-To: <20190104093808.GJ31793@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> Message-ID: <4630dd7797fc7934f98c01ea789105a8@suse.de> X-Sender: rpenyaev@suse.de User-Agent: Roundcube Webmail Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Roman