Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936186AbdCVT3l (ORCPT ); Wed, 22 Mar 2017 15:29:41 -0400 Received: from mail-io0-f173.google.com ([209.85.223.173]:35843 "EHLO mail-io0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758909AbdCVT30 (ORCPT ); Wed, 22 Mar 2017 15:29:26 -0400 MIME-Version: 1.0 In-Reply-To: <1488827386-87193-6-git-send-email-keescook@chromium.org> References: <1488827386-87193-1-git-send-email-keescook@chromium.org> <1488827386-87193-6-git-send-email-keescook@chromium.org> From: Kees Cook Date: Wed, 22 Mar 2017 12:29:24 -0700 X-Google-Sender-Auth: jXgsnIT4UZxA4esia-MDL8-t65Y Message-ID: Subject: Re: [PATCH 5/6] notifiers: Use CHECK_DATA_CORRUPTION() on checks To: Arjan van de Ven Cc: Kees Cook , Andrew Morton , Rik van Riel , "Paul E. McKenney" , Jakub Kicinski , Viresh Kumar , Ingo Molnar , Thomas Gleixner , Dmitry Vyukov , Olof Johansson , Peter Zijlstra , Josh Poimboeuf , LKML , "kernel-hardening@lists.openwall.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2208 Lines: 64 On Mon, Mar 6, 2017 at 11:09 AM, Kees Cook wrote: > When performing notifier function pointer sanity checking, allow > CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG. > Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting > CONFIG_BUG_ON_DATA_CORRUPTION. Any feedback on this change? By default, this retains the existing WARN behavior... -Kees > > Signed-off-by: Kees Cook > --- > kernel/notifier.c | 5 +++-- > lib/Kconfig.debug | 3 ++- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/notifier.c b/kernel/notifier.c > index 6196af8a8223..58cc14958d92 100644 > --- a/kernel/notifier.c > +++ b/kernel/notifier.c > @@ -84,8 +84,9 @@ static int notifier_call_chain(struct notifier_block **nl, > next_nb = rcu_dereference_raw(nb->next); > > #ifdef CONFIG_DEBUG_NOTIFIERS > - if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) { > - WARN(1, "Invalid notifier called!"); > + if (CHECK_DATA_CORRUPTION( > + !func_ptr_is_kernel_text(nb->notifier_call), > + "Invalid notifier called!")) { > nb = next_nb; > continue; > } > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 42c61cfe7d19..70e9f2c1bb30 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1277,7 +1277,7 @@ config DEBUG_SG > > config DEBUG_NOTIFIERS > bool "Debug notifier call chains" > - depends on DEBUG_KERNEL > + depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION > help > Enable this to turn on sanity checking for notifier call chains. > This is most useful for kernel developers to make sure that > @@ -1995,6 +1995,7 @@ config BUG_ON_DATA_CORRUPTION > bool "Trigger a BUG when data corruption is detected" > select DEBUG_CREDENTIALS > select DEBUG_LIST > + select DEBUG_NOTIFIERS > select DEBUG_SG > help > This option enables several inexpensive data corruption checks. > -- > 2.7.4 > -- Kees Cook Pixel Security