Commit fd432b9f authored Nov 06, 2013 by Aaron Lu Committed by Rafael J. Wysocki Nov 07, 2013

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>

parent 7bc9b1cf

kernel/power/snapshot.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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. */