From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756755AbdACIo3 (ORCPT ); Tue, 3 Jan 2017 03:44:29 -0500 Received: from mx2.suse.de ([195.135.220.15]:37030 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751851AbdACIoW (ORCPT ); Tue, 3 Jan 2017 03:44:22 -0500 Date: Tue, 3 Jan 2017 09:44:19 +0100 From: Michal Hocko To: Anshuman Khandual Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, vbabka@suse.cz, akpm@linux-foundation.org Subject: Re: [RFC] nodemask: Consider MAX_NUMNODES inside node_isset Message-ID: <20170103084418.GC30111@dhcp22.suse.cz> References: <20170103082753.25758-1-khandual@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170103082753.25758-1-khandual@linux.vnet.ibm.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 03-01-17 13:57:53, Anshuman Khandual wrote: > node_isset can give incorrect result if the node number is beyond the > bitmask size (MAX_NUMNODES in this case) which is not checked inside > test_bit. Hence check for the bit limits (MAX_NUMNODES) inside the > node_isset function before calling test_bit. Could you be more specific when such a thing might happen? Have you seen any in-kernel user who would give such a bogus node? > Signed-off-by: Anshuman Khandual > --- > include/linux/nodemask.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h > index 6e66cfd..0aee588b 100644 > --- a/include/linux/nodemask.h > +++ b/include/linux/nodemask.h > @@ -139,7 +139,13 @@ static inline void __nodes_clear(nodemask_t *dstp, unsigned int nbits) > } > > /* No static inline type checking - see Subtlety (1) above. */ > -#define node_isset(node, nodemask) test_bit((node), (nodemask).bits) > +#define node_isset(node, nodemask) node_test_bit(node, nodemask, MAX_NUMNODES) > +static inline int node_test_bit(int node, nodemask_t nodemask, int maxnodes) > +{ > + if (node >= maxnodes) > + return 0; > + return test_bit((node), (nodemask).bits); > +} > > #define node_test_and_set(node, nodemask) \ > __node_test_and_set((node), &(nodemask)) > -- > 1.8.3.1 > -- Michal Hocko SUSE Labs