From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miles Chen Subject: Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug messages Date: Fri, 9 Aug 2019 22:11:58 +0800 Message-ID: <1565359918.12824.20.camel@mtkswgap22> References: <20190809010837.24166-1-miles.chen@mediatek.com> <20190809024644.GL5482@bombadil.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190809024644.GL5482@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Matthew Wilcox Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com, "Tobin C . Harding" , Kees Cook List-Id: linux-mediatek@lists.infradead.org On Thu, 2019-08-08 at 19:46 -0700, Matthew Wilcox wrote: > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote: > > Possible approaches are: > > 1. stop printing kernel addresses > > 2. print with %pK, > > 3. print with %px. > > No. The point of obscuring kernel addresses is that if the attacker manages to find a way to get the kernel to spit out some debug messages that we shouldn't > leak all this extra information. got it. > > > 4. do nothing > > 5. Find something more useful to print. agree > > > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) > > ... you don't have any randomness on your platform? We have randomized base on our platforms. > But if you have randomness, at least some of these "pointers" are valuable > because you can compare them against "pointers" printed by other parts > of the kernel. Understood. Keep current %p, do not leak kernel addresses. I'll collect more cases and see if we really need some extra information. (maybe the @offset in current message is enough) thanks for your comments!