From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754494AbdDKLIN (ORCPT ); Tue, 11 Apr 2017 07:08:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:34882 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752398AbdDKLIK (ORCPT ); Tue, 11 Apr 2017 07:08:10 -0400 From: Petr Mladek To: Josh Poimboeuf , Miroslav Benes Cc: Jessica Yu , Jiri Kosina , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Petr Mladek Subject: [PATCH] livepatch: Cancel transition a safe way for immediate patches Date: Tue, 11 Apr 2017 13:07:48 +0200 Message-Id: <1491908868-27766-1-git-send-email-pmladek@suse.com> X-Mailer: git-send-email 1.8.5.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org klp_init_transition() does not set func->transition for immediate patches. Then klp_ftrace_handler() could use the new code immediately. As a result, it is not safe to put the livepatch module in klp_cancel_transition(). This patch reverts most of the last minute changes klp_cancel_transition(). It keeps the warning about a misuse because it still makes sense. Signed-off-by: Petr Mladek --- Hi, I am afraid that Mirek was not right in the mail https://lkml.kernel.org/r/alpine.LSU.2.20.1702161504020.16310@pobox.suse.cz IMHO, it is not safe to put the module when the immediate patch cannot be applied. Best Regards, Petr kernel/livepatch/transition.c | 20 -------------------- 1 file changed, 20 deletions(-) diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 2de09e0c4e5c..adc0cc64aa4b 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -120,31 +120,11 @@ static void klp_complete_transition(void) */ void klp_cancel_transition(void) { - struct klp_patch *patch = klp_transition_patch; - struct klp_object *obj; - struct klp_func *func; - bool immediate_func = false; - if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED)) return; klp_target_state = KLP_UNPATCHED; klp_complete_transition(); - - /* - * In the enable error path, even immediate patches can be safely - * removed because the transition hasn't been started yet. - * - * klp_complete_transition() doesn't have a module_put() for immediate - * patches, so do it here. - */ - klp_for_each_object(patch, obj) - klp_for_each_func(obj, func) - if (func->immediate) - immediate_func = true; - - if (patch->immediate || immediate_func) - module_put(patch->mod); } /* -- 1.8.5.6