From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 31B276B0253 for ; Fri, 6 Oct 2017 17:38:34 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id v13so33180117pgq.1 for ; Fri, 06 Oct 2017 14:38:34 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTPS id k197si1791151pgc.187.2017.10.06.14.38.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Oct 2017 14:38:33 -0700 (PDT) From: Luis Felipe Sandoval Castro Subject: [PATCH v1] mm/mempolicy.c: Fix get_nodes() off-by-one error. Date: Fri, 6 Oct 2017 08:36:34 -0500 Message-Id: <1507296994-175620-2-git-send-email-luis.felipe.sandoval.castro@intel.com> In-Reply-To: <1507296994-175620-1-git-send-email-luis.felipe.sandoval.castro@intel.com> References: <1507296994-175620-1-git-send-email-luis.felipe.sandoval.castro@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com, mingo@kernel.org, rientjes@google.com, n-horiguchi@ah.jp.nec.com, salls@cs.ucsb.edu, Luis Felipe Sandoval Castro set_mempolicy() and mbind() take as argument a pointer to a bit mask (nodemask) and the number of bits in the mask the kernel will use (maxnode), among others. For instace on a system with 2 NUMA nodes valid masks are: 0b00, 0b01, 0b10 and 0b11 it's clear maxnode=2, however an off-by-one error in get_nodes() the function that copies the node mask from user space requires users to pass maxnode = 3 in this example and maxnode = actual_maxnode + 1 in the general case. This patch fixes such error. Signed-off-by: Luis Felipe Sandoval Castro --- mm/mempolicy.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 006ba62..0c2e3cd 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1265,11 +1265,10 @@ 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) + if (maxnode == 1 || !nmask) return 0; - if (maxnode > PAGE_SIZE*BITS_PER_BYTE) + if (maxnode - 1 > PAGE_SIZE * BITS_PER_BYTE) return -EINVAL; nlongs = BITS_TO_LONGS(maxnode); -- 1.8.3.1 -- 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