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PM / hibernate: Avoid overflow in hibernate_preallocate_memory()

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commit fd432b9f8c upstream.

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>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Aaron Lu
2013-11-06 08:41:31 +08:00
committed by Greg Kroah-Hartman
parent d8db1a5f31
commit 67b51f87ef
1 changed files with 5 additions and 1 deletions
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6
kernel/power/snapshot.c
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@@ -1398,7 +1398,11 @@ int hibernate_preallocate_memory(void)
* highmem and non-highmem zones separately. * highmem and non-highmem zones separately.
*/ */
pages_highmem = preallocate_image_highmem(highmem / 2); 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); pages = preallocate_image_memory(alloc, avail_normal);
if (pages < alloc) { if (pages < alloc) {
/* We have exhausted non-highmem pages, try highmem. */ /* We have exhausted non-highmem pages, try highmem. */