From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751524AbdJaIfB (ORCPT ); Tue, 31 Oct 2017 04:35:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:44185 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751119AbdJaIe6 (ORCPT ); Tue, 31 Oct 2017 04:34:58 -0400 Subject: Re: [PATCH RFC v2 1/4] mm/mempolicy: Fix get_nodes() mask miscalculation To: Yisheng Xie , akpm@linux-foundation.org, mhocko@suse.com, mingo@kernel.org, rientjes@google.com, n-horiguchi@ah.jp.nec.com, salls@cs.ucsb.edu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, tanxiaojun@huawei.com, linux-api@vger.kernel.org, Andi Kleen References: <1509099265-30868-1-git-send-email-xieyisheng1@huawei.com> <1509099265-30868-2-git-send-email-xieyisheng1@huawei.com> From: Vlastimil Babka Message-ID: <922a4767-9eed-40aa-c437-6f6fcdcab150@suse.cz> Date: Tue, 31 Oct 2017 09:34:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <1509099265-30868-2-git-send-email-xieyisheng1@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/27/2017 12:14 PM, Yisheng Xie wrote: > It appears there is a nodemask miscalculation in the get_nodes() > function in mm/mempolicy.c. This bug has two effects: > > 1. It is impossible to specify a length 1 nodemask. > 2. It is impossible to specify a nodemask containing the last node. This should be more specific, which syscalls are you talking about? I assume it's set_mempolicy() and mbind() and it's the same issue that was discussed at https://marc.info/?l=linux-mm&m=150732591909576&w=2 ? > Brent have submmit a patch before v2.6.12, however, Andi revert his > changed for ABI problem. I just resent this patch as RFC, for do not > clear about what's the problem Andi have met. You should have CC'd Andi. As was discussed in the other thread, this would make existing programs potentially unsafe, so we can't change it. Instead it should be documented. > As manpage of set_mempolicy, If the value of maxnode is zero, the > nodemask argument is ignored. but we should not ignore the nodemask > when maxnode is 1. > > Signed-off-by: Yisheng Xie > --- > mm/mempolicy.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index a2af6d5..613e9d0 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1265,7 +1265,6 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, > unsigned long nlongs; > unsigned long endmask; > > - --maxnode; > nodes_clear(*nodes); > if (maxnode == 0 || !nmask) > return 0; > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlastimil Babka Subject: Re: [PATCH RFC v2 1/4] mm/mempolicy: Fix get_nodes() mask miscalculation Date: Tue, 31 Oct 2017 09:34:54 +0100 Message-ID: <922a4767-9eed-40aa-c437-6f6fcdcab150@suse.cz> References: <1509099265-30868-1-git-send-email-xieyisheng1@huawei.com> <1509099265-30868-2-git-send-email-xieyisheng1@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1509099265-30868-2-git-send-email-xieyisheng1@huawei.com> Content-Language: en-US Sender: owner-linux-mm@kvack.org To: Yisheng Xie , akpm@linux-foundation.org, mhocko@suse.com, mingo@kernel.org, rientjes@google.com, n-horiguchi@ah.jp.nec.com, salls@cs.ucsb.edu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, tanxiaojun@huawei.com, linux-api@vger.kernel.org, Andi Kleen List-Id: linux-api@vger.kernel.org On 10/27/2017 12:14 PM, Yisheng Xie wrote: > It appears there is a nodemask miscalculation in the get_nodes() > function in mm/mempolicy.c. This bug has two effects: > > 1. It is impossible to specify a length 1 nodemask. > 2. It is impossible to specify a nodemask containing the last node. This should be more specific, which syscalls are you talking about? I assume it's set_mempolicy() and mbind() and it's the same issue that was discussed at https://marc.info/?l=linux-mm&m=150732591909576&w=2 ? > Brent have submmit a patch before v2.6.12, however, Andi revert his > changed for ABI problem. I just resent this patch as RFC, for do not > clear about what's the problem Andi have met. You should have CC'd Andi. As was discussed in the other thread, this would make existing programs potentially unsafe, so we can't change it. Instead it should be documented. > As manpage of set_mempolicy, If the value of maxnode is zero, the > nodemask argument is ignored. but we should not ignore the nodemask > when maxnode is 1. > > Signed-off-by: Yisheng Xie > --- > mm/mempolicy.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index a2af6d5..613e9d0 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1265,7 +1265,6 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, > unsigned long nlongs; > unsigned long endmask; > > - --maxnode; > nodes_clear(*nodes); > if (maxnode == 0 || !nmask) > return 0; > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org