From fd432b9f8c7c88428a4635b9f5a9c6e174df6e36 Mon Sep 17 00:00:00 2001
From: Aaron Lu <aaron.lu@intel.com>
Date: Wed, 6 Nov 2013 08:41:31 +0800
Subject: 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.
References: https://bugzilla.kernel.org/show_bug.cgi?id=60817
Reported-and-tested-by: Leon Drugi <eyak@wp.pl>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
kernel/power/snapshot.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
(limited to 'kernel/power')
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. */
--
cgit