Return-Path: linux-nfs-owner@vger.kernel.org Received: from aserp1040.oracle.com ([141.146.126.69]:35725 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbbBWPog (ORCPT ); Mon, 23 Feb 2015 10:44:36 -0500 Date: Mon, 23 Feb 2015 18:44:19 +0300 From: Dan Carpenter To: "Eric W. Biederman" Cc: Andrew Morton , Andy Lutomirski , Wang YanQing , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [patch] groups: integer underflow in groups_alloc() Message-ID: <20150223154419.GA2542@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-nfs-owner@vger.kernel.org List-ID: This is called from rsc_parse() with a use controlled value. Say for example that "gidsetsize" is negative, then we could end up allocating less than sizeof(struct group_info) leading to memory corruption. Signed-off-by: Dan Carpenter --- I copied the NGROUPS_MAX limit from the surrounding code, I'm not absolutely that it's the correct limit to use. diff --git a/kernel/groups.c b/kernel/groups.c index 664411f..e9341b3 100644 --- a/kernel/groups.c +++ b/kernel/groups.c @@ -18,6 +18,9 @@ struct group_info *groups_alloc(int gidsetsize) int nblocks; int i; + if ((unsigned)gidsetsize > NGROUPS_MAX) + return NULL; + nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; /* Make sure we always allocate at least one indirect block pointer */ nblocks = nblocks ? : 1;