From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1033233AbeBNRBk (ORCPT ); Wed, 14 Feb 2018 12:01:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:46721 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032907AbeBNRBj (ORCPT ); Wed, 14 Feb 2018 12:01:39 -0500 Date: Wed, 14 Feb 2018 18:01:33 +0100 From: Borislav Petkov To: Josh Poimboeuf Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Peter Zijlstra , Jason Baron Subject: Re: [PATCH 1/3] jump_label: Warn on failed jump_label patch Message-ID: <20180214170133.GA19502@pd.tnic> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 14, 2018 at 10:40:41AM -0600, Josh Poimboeuf wrote: > When the jump label code encounters an address which isn't recognized by > kernel_text_address(), it just silently fails. > > This can be dangerous because jump labels are used in a variety of > places, and are generally expected to work. Convert the silent failure > to a warning. > > Signed-off-by: Josh Poimboeuf > --- > kernel/jump_label.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/kernel/jump_label.c b/kernel/jump_label.c > index b4517095db6a..c71fb7cdfc41 100644 > --- a/kernel/jump_label.c > +++ b/kernel/jump_label.c > @@ -370,8 +370,12 @@ static void __jump_label_update(struct static_key *key, > * kernel_text_address() verifies we are not in core kernel > * init code, see jump_label_invalidate_module_init(). > */ > - if (entry->code && kernel_text_address(entry->code)) > - arch_jump_label_transform(entry, jump_label_type(entry)); > + if (entry->code) { > + if (kernel_text_address(entry->code)) > + arch_jump_label_transform(entry, jump_label_type(entry)); > + else > + WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code); > + } > } > } > > -- > 2.14.3 Good idea. Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --