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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D4014C4727C for ; Fri, 25 Sep 2020 13:23:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD5A1239EC for ; Fri, 25 Sep 2020 13:23:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728692AbgIYNXp (ORCPT ); Fri, 25 Sep 2020 09:23:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:44704 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728643AbgIYNXo (ORCPT ); Fri, 25 Sep 2020 09:23:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6B7F9B509; Fri, 25 Sep 2020 13:07:01 +0000 (UTC) Date: Fri, 25 Sep 2020 15:06:55 +0200 (CEST) From: Miroslav Benes To: Kristen Carlson Accardi cc: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arjan@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, live-patching@vger.kernel.org Subject: Re: [PATCH v5 00/10] Function Granular KASLR In-Reply-To: <20200923173905.11219-1-kristen@linux.intel.com> Message-ID: References: <20200923173905.11219-1-kristen@linux.intel.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kristen, On Wed, 23 Sep 2020, Kristen Carlson Accardi wrote: > Function Granular Kernel Address Space Layout Randomization (fgkaslr) > --------------------------------------------------------------------- > > This patch set is an implementation of finer grained kernel address space > randomization. It rearranges your kernel code at load time > on a per-function level granularity, with only around a second added to > boot time. I ran live patching kernel selftests on the patch set and everything passed fine. However, we also use not-yet-upstream set of tests at SUSE for testing live patching [1] and one of them, klp_tc_12.sh, is failing. You should be able to run the set on upstream as is. The test uninterruptedly sleeps in a kretprobed function called by a patched one. The current master without fgkaslr patch set reports the stack of the sleeping task as unreliable and live patching fails. The situation is different with fgkaslr (even with nofgkaslr on the command line). The stack is returned as reliable. It looks something like [<0>] __schedule+0x465/0xa40 [<0>] schedule+0x55/0xd0 [<0>] orig_do_sleep+0xb1/0x110 [klp_test_support_mod] [<0>] swap_pages+0x7f/0x7f where the last entry is not reliable. I've seen kretprobe_trampoline+0x0/0x4a and some other symbols there too. Since the patched function (orig_sleep_uninterruptible_set) is not on the stack, live patching succeeds, which is not intended. With kprobe setting removed, all works as expected. So I wonder if there is still some issue with ORC somewhere as you mentioned in v4 thread. I'll investigate more next week, but wanted to report early. Regards Miroslav [1] https://github.com/lpechacek/qa_test_klp