From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 7BD648E00AE for ; Fri, 4 Jan 2019 05:21:42 -0500 (EST) Received: by mail-ed1-f69.google.com with SMTP id t2so34729544edb.22 for ; Fri, 04 Jan 2019 02:21:42 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id g21si2990937edj.72.2019.01.04.02.21.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Jan 2019 02:21:40 -0800 (PST) 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 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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