From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Lu Subject: [PATCH update] PM / hibernate: Avoid overflow in hibernate_preallocate_memory Date: Wed, 06 Nov 2013 08:41:31 +0800 Message-ID: <5279903B.40202@intel.com> References: <52789B31.70005@intel.com> <1974778.1p97Y6DIEX@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com ([134.134.136.24]:52711 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755373Ab3KFAkr (ORCPT ); Tue, 5 Nov 2013 19:40:47 -0500 In-Reply-To: <1974778.1p97Y6DIEX@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" Cc: Linux-pm mailing list , Leon Drugi On 11/05/2013 10:22 PM, Rafael J. Wysocki wrote: > On Tuesday, November 05, 2013 03:16:01 PM Aaron Lu wrote: >> pages_highmem = preallocate_image_highmem(highmem / 2); >> - alloc = (count - max_size) - pages_highmem; >> + alloc = (count - max_size) > pages_highmem ? >> + (count - max_size - pages_highmem) : 0; > > Well, what about > > alloc = count - max_size; > if (alloc > pages_highmem) > alloc -= pages_highmem; > else > alloc = 0; > OK, here it comes: From: Aaron Lu Subject: [PATCH] PM / hibernate: Avoid overflow in hibernate_preallocate_memory When system has a lot of highmem(e.g. 16GiB using a 32 bits kernel), the code to calculate how much memory we need to preallocate in normal zone may cause overflow. As Leon has analysed: " It looks that during computing 'alloc' variable there is overflow: alloc = (3943404 - 1970542) - 1978280 = -5418 (signed) And this function goes to err_out. " Fix this by avoiding that overflow. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=60817 Reported-and-tested-by: Leon Drugi Cc: stable Signed-off-by: Aaron Lu --- kernel/power/snapshot.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 98c3b34a4cff..10c22cae83a0 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1402,7 +1402,11 @@ int hibernate_preallocate_memory(void) * highmem and non-highmem zones separately. */ pages_highmem = preallocate_image_highmem(highmem / 2); - alloc = (count - max_size) - pages_highmem; + alloc = count - max_size; + if (alloc > pages_highmem) + alloc -= pages_highmem; + else + alloc = 0; pages = preallocate_image_memory(alloc, avail_normal); if (pages < alloc) { /* We have exhausted non-highmem pages, try highmem. */ -- 1.8.4.39.ga0d3f10