Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755763AbaBEUvr (ORCPT ); Wed, 5 Feb 2014 15:51:47 -0500 Received: from mail1.windriver.com ([147.11.146.13]:48240 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754744AbaBEUF6 (ORCPT ); Wed, 5 Feb 2014 15:05:58 -0500 From: Paul Gortmaker To: , CC: T Makphaibulchoke , Paul Gortmaker , Wei Yang , Andrew Morton , Linus Torvalds , Paul Gortmaker Subject: [v2.6.34-stable 092/213] kernel/resource.c: fix stack overflow in __reserve_region_with_split() Date: Wed, 5 Feb 2014 15:00:47 -0500 Message-ID: <1391630568-49251-93-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.8.5.2 In-Reply-To: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> References: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: T Makphaibulchoke ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 4965f5667f36a95b41cda6638875bc992bd7d18b upstream. Using a recursive call add a non-conflicting region in __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 Reviewed-by: Ram Pai Cc: Paul Gortmaker Cc: Wei Yang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Paul Gortmaker --- kernel/resource.c | 50 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 12 deletions(-) diff --git a/kernel/resource.c b/kernel/resource.c index 9c358e263534..bb76480a566f 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -613,6 +613,7 @@ 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; @@ -622,21 +623,46 @@ 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, -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/