From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758352Ab2IGWIX (ORCPT ); Fri, 7 Sep 2012 18:08:23 -0400 Received: from g5t0008.atlanta.hp.com ([15.192.0.45]:39481 "EHLO g5t0008.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751101Ab2IGWIW (ORCPT ); Fri, 7 Sep 2012 18:08:22 -0400 From: T Makphaibulchoke To: akpm@linux-foundation.org, linuxram@us.ibm.com, paul.gortmaker@windriver.com, weiyang@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Cc: T Makphaibulchoke Subject: [PATCH v3] kernel/resource.c: fix stack overflow in __reserve_region_with_split Date: Fri, 7 Sep 2012 16:08:19 -0600 Message-Id: <1347055699-3468-1-git-send-email-tmac@hp.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using recurvise call to try adding a non-conflicting region in the function __reserve_region_with_split() could result in a stack overflow in the case that the recursive calls are too deep. Convert the recursive calls to an iterative loop to avoid the problem. Tested on a machine containing 135 regions. The kernel no longer panicked with stack overflow. Also tested with code arbitrarily adding regions with no conflict, embedding two consecutive conflicts and embedding two non-consecutive conflicts. Signed-off-by: T Makphaibulchoke --- Change since v2: * Initializing both the name and flags fileds of the newly allocated region request. Change since v1: * Fixing __resrve_region_with_split() to ensure a reqion reserve request is satisfied to the fullest extent, minus any overlapping conflicting regions. --- kernel/resource.c | 50 ++++++++++++++++++++++++++++++++++++++------------ 1 files changed, 38 insertions(+), 12 deletions(-) diff --git a/kernel/resource.c b/kernel/resource.c index 34d4588..73f35d4 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -763,6 +763,7 @@ static void __init __reserve_region_with_split(struct resource *root, struct resource *parent = root; struct resource *conflict; struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC); + struct resource *next_res = NULL; if (!res) return; @@ -772,21 +773,46 @@ static void __init __reserve_region_with_split(struct resource *root, res->end = end; res->flags = IORESOURCE_BUSY; - conflict = __request_resource(parent, res); - if (!conflict) - return; + while (1) { - /* failed, split and try again */ - kfree(res); + conflict = __request_resource(parent, res); + if (!conflict) { + if (!next_res) + break; + res = next_res; + next_res = NULL; + continue; + } - /* conflict covered whole area */ - if (conflict->start <= start && conflict->end >= end) - return; + /* conflict covered whole area */ + if (conflict->start <= res->start && + conflict->end >= res->end) { + kfree(res); + WARN_ON(next_res); + break; + } + + /* failed, split and try again */ + if (conflict->start > res->start) { + end = res->end; + res->end = conflict->start - 1; + if (conflict->end < end) { + next_res = kzalloc(sizeof(*next_res), + GFP_ATOMIC); + if (!next_res) { + kfree(res); + break; + } + next_res->name = name; + next_res->start = conflict->end + 1; + next_res->end = end; + next_res->flags = IORESOURCE_BUSY; + } + } else { + res->start = conflict->end + 1; + } + } - if (conflict->start > start) - __reserve_region_with_split(root, start, conflict->start-1, name); - if (conflict->end < end) - __reserve_region_with_split(root, conflict->end+1, end, name); } void __init reserve_region_with_split(struct resource *root, -- 1.7.1