From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755238Ab1AaIwS (ORCPT ); Mon, 31 Jan 2011 03:52:18 -0500 Received: from a.mx.secunet.com ([195.81.216.161]:35808 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754978Ab1AaIwQ (ORCPT ); Mon, 31 Jan 2011 03:52:16 -0500 Date: Mon, 31 Jan 2011 09:52:13 +0100 From: Steffen Klassert To: Dave Hansen Cc: Andrew Morton , Eric Paris , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH] flex_array: Change behaviour on zero size allocations Message-ID: <20110131085213.GK3070@secunet.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 31 Jan 2011 08:52:13.0986 (UTC) FILETIME=[27BCD020:01CBC124] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org flex_array_alloc allocates the basic struct flex_array regardless whether total_nr_elements or element_size is zero. Then flex_array_prealloc fails with -ENOSPC if total_nr_elements is zero or it hits a division by zero if element_size is zero. This patch changes the behaviour on zero size allocations to the same as kmalloc, so zero size allocations are leagal now. This fixes a regression on selinux policy loading. Signed-off-by: Steffen Klassert --- lib/flex_array.c | 25 +++++++++++++++++++++---- 1 files changed, 21 insertions(+), 4 deletions(-) diff --git a/lib/flex_array.c b/lib/flex_array.c index c0ea40b..8eb437b 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -88,8 +88,11 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total, gfp_t flags) { struct flex_array *ret; - int max_size = FLEX_ARRAY_NR_BASE_PTRS * - FLEX_ARRAY_ELEMENTS_PER_PART(element_size); + int max_size = 0; + + if (element_size) + max_size = FLEX_ARRAY_NR_BASE_PTRS * + FLEX_ARRAY_ELEMENTS_PER_PART(element_size); /* max_size will end up 0 if element_size > PAGE_SIZE */ if (total > max_size) @@ -183,15 +186,18 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags) int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, gfp_t flags) { - int part_nr = fa_element_to_part_nr(fa, element_nr); + int part_nr; struct flex_array_part *part; void *dst; + if (!fa->element_size) + return 0; if (element_nr >= fa->total_nr_elements) return -ENOSPC; if (elements_fit_in_base(fa)) part = (struct flex_array_part *)&fa->parts[0]; else { + part_nr = fa_element_to_part_nr(fa, element_nr); part = __fa_get_part(fa, part_nr, flags); if (!part) return -ENOMEM; @@ -211,15 +217,18 @@ EXPORT_SYMBOL(flex_array_put); */ int flex_array_clear(struct flex_array *fa, unsigned int element_nr) { - int part_nr = fa_element_to_part_nr(fa, element_nr); + int part_nr; struct flex_array_part *part; void *dst; + if (!fa->element_size) + return 0; if (element_nr >= fa->total_nr_elements) return -ENOSPC; if (elements_fit_in_base(fa)) part = (struct flex_array_part *)&fa->parts[0]; else { + part_nr = fa_element_to_part_nr(fa, element_nr); part = fa->parts[part_nr]; if (!part) return -EINVAL; @@ -252,8 +261,12 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start, int part_nr; struct flex_array_part *part; + if (!fa->total_nr_elements) + return 0; if (start >= fa->total_nr_elements || end >= fa->total_nr_elements) return -ENOSPC; + if (!fa->element_size) + return 0; if (elements_fit_in_base(fa)) return 0; start_part = fa_element_to_part_nr(fa, start); @@ -284,6 +297,8 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr) int part_nr = fa_element_to_part_nr(fa, element_nr); struct flex_array_part *part; + if (!fa->total_nr_elements || !fa->element_size) + return NULL; if (element_nr >= fa->total_nr_elements) return NULL; if (elements_fit_in_base(fa)) @@ -343,6 +358,8 @@ int flex_array_shrink(struct flex_array *fa) int part_nr; int ret = 0; + if (!fa->total_nr_elements || !fa->element_size) + return 0; if (elements_fit_in_base(fa)) return ret; for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) { -- 1.7.0.4